Stand beneath a large and old tree on a sweltering summer afternoon and the difference is immediate. The air out may feel heavy, the pavement may be radiating heat, and the buildings may trap the warmth around you. Yet beneath the canopy, there is shade, cooler air and a sense of relief.
The shade, provided by the urban trees is not decoration. It is infrastructure. Trees cool neighborhoods, they help in making rain, absorb stormwater, filter pollutants from the air and provide habitat for wildlife. They also create places where people can walk, rest, exercise and escape the pressure of increasingly hot and crowded cities.
Yet cities around the world still too often treat urban trees as an aesthetic extra rather than as essential infrastructure. However, that approach now needs a change.
Why Urban Trees Are More Than Just A Pretty Face
Urban trees are far more than just a decoration. In this context, a major scientific assessment involving more than 60 researchers from numerous countries is now calling for that approach to change.
Led by Manuel Esperon-Rodriguez of Western Sydney University and Bangor University, with Mark G. Tjoelker of Western Sydney University as senior author, the researchers argue that urban forests must be elevated from something that is simply “nice to have” to something cities are required to protect and maintain.
A tree planted today cannot replace a tree lost yesterday. A sapling can be planted in minutes. A mature canopy cannot. It may take decades for a young tree to grow large enough to provide the shade, cooling, habitat and carbon storage of an established tree.
When a mature tree is removed, a city therefore loses far more than a piece of vegetation. It loses years – sometimes decades – of environmental services that cannot simply be replaced by planting another sapling. Yet mature trees continue to disappear when development takes priority over preservation. In many cases, planting is celebrated while maintenance is neglected.
Trees need water, pruning, protection from pests and enough space to develop healthy root systems. Without long-term care, even ambitious tree-planting campaigns can fail.
The researchers therefore call for stronger enforcement against unnecessary tree removal, meaningful incentives for landowners who preserve mature trees and legal requirements for minimum urban canopy cover. Even major infrastructure projects, they argue, should be redesigned where possible to incorporate and expand tree cover rather than automatically removing it.
The neighborhoods suffering most from heat often have the fewest trees
There is another problem hidden beneath the city canopy: inequality. Urban greenery is rarely distributed evenly. Wealthier neighborhoods tend to have more trees and greater canopy cover, while lower-income communities are often exposed to greater heat and poorer air quality.
The result is a cruel imbalance: the people who may have fewer resources to protect themselves from extreme heat can also have less natural protection around them. A citywide average can conceal this inequality.
One part of a city may be filled with mature trees while another neighborhood remains almost entirely exposed to concrete and asphalt. For that reason, the researchers argue that urban canopy targets should be established neighborhood by neighborhood rather than judged only through citywide statistics.
Greening cities must not push people out
Planting trees sounds like an uncomplicated solution. It is not always. New green spaces can make neighborhoods more attractive and, in some cases, more expensive. This can contribute to “green gentrification,” where improvements intended to benefit residents ultimately increase rents and push some of those residents away. That creates a difficult contradiction: a neighborhood receives more trees but the people who were supposed to benefit from them can no longer afford to live there. The researchers therefore argue that tree policy and housing policy should not operate in isolation.
Communities themselves must also have a voice in deciding what is planted and where. Residents may have different needs and preferences – from fruit-bearing trees to species that produce less pollen or are better suited to local conditions. Indigenous communities and local knowledge should be part of planning process.
Urban forests are a climate solution hiding in plain sight
As cities struggle with rising temperatures, heavier rainfall and worsening air pollution, trees are already performing many of the functions governments are trying to achieve through expensive climate adaptation measures. Their canopies provide shade and reduce temperatures.
Their vegetation releases water vapor and contributes to cooling. Green spaces can help stormwater enter the ground rather than rapidly accumulating on streets and causing floods, while trees and other vegetation absorb pollutants from the air.
Parks and green spaces also support physical and mental well-being, whereas urban agriculture can provide food and employment to the citizens. Trees are, in other words, working quietly across several fronts at once. Yet urban forests remain surprisingly absent from many major climate and biodiversity strategies.
The researchers argue that urban forests should be explicitly incorporated into national climate plans, biodiversity strategies and international commitments. Their argument is straightforward: if trees are helping cities adapt to climate change, then protecting them should be part of climate policy rather than an afterthought.
Planting a tree is only the beginning
One of the biggest weaknesses in urban forestry is funding. Governments and organizations can be enthusiastic about planting ceremonies, new saplings and public announcements. But the difficult work begins afterward. Young trees need years of watering and protection before they become established.
They need pruning, monitoring and protection from pests and disease. A tree that dies a few years after planting may still have appeared in a successful planting statistic. But environmentally, it is a failure. That is why the researchers argue that cities need dedicated budgets for urban forests rather than treating trees as one-time projects. The economic argument matters too. Green spaces can generate benefits by encouraging exercise, supporting public health and attracting people into surrounding neighborhoods, where their presence can stimulate local economic activity.
Many cities do not even know which trees are surviving
There is another problem that receives less attention: data. Some cities do not maintain reliable records of their urban trees. They may not know which newly planted saplings survived their first few summers, which species are struggling, or how evenly tree canopy is distributed across neighborhoods.
Without that information, officials are effectively managing urban forests in the dark. Satellite imagery, artificial intelligence-assisted monitoring and other lower-cost technologies could help cities track canopy cover, tree survival and changing conditions – particularly in places where resources are limited.
Better data could also make governments more accountable. If a city promises to increase tree cover, residents should eventually be able to see whether that promise has actually been fulfilled.
Cities should stop putting all their trees in the same basket
More trees do not automatically mean a healthier urban forest. Diversity matters. Planting the same handful of species across an entire city may create an attractive landscape, but it can also create vulnerability. A single pest or disease capable of attacking one species could potentially spread through large sections of the urban canopy. Researchers therefore recommend greater diversity in urban tree populations.
Native species should remain important, particularly because they can support local ecosystems and reflect the ecological and cultural character of a place. But carefully selected non-native species may also have a role where they are better adapted to increasingly hot and dry conditions.
The question is not simply: What tree can we plant today? It is: What trees will survive the climate of tomorrow?
The next 50 years are being decided today
Cities are growing. Heatwaves are intensifying. Extreme rainfall is becoming a greater challenge. And the decisions being made today about urban trees will remain visible for decades. A mature tree cannot be manufactured overnight. It cannot be replaced simply by ordering hundreds of seedlings. Its value accumulates slowly, season after season, year after year. That makes every mature tree standing in a city a kind of living climate investment.
The researchers’ message is therefore both simple and urgent: urban trees must move from the margins of city planning to the center of it. They should be protected by law, supported by dedicated funding, monitored with reliable data and distributed fairly across neighborhoods. Most importantly, cities need to think beyond planting targets. A tree planted today must be able to survive the next 10, 20 or even 50 years.
Trees are not decoration. They are city infrastructure.
For generations, urban trees have been treated as pleasant additions to streets, parks and public spaces. That thinking is becoming dangerously outdated. Trees cool the concrete jungle. They help manage stormwater. They improve air quality. They provide habitat. They support physical and mental health. And for people living in the hottest and most underserved neighborhoods, they can provide a crucial shield against extreme urban heat.
Scientists are now calling for cities to treat these benefits as essential public infrastructure rather than optional beautification. The choice facing city leaders is therefore bigger than whether to plant more trees. It is whether to protect the trees cities already have, invest in the trees they need, and ensure that every neighborhood – not only the wealthiest – receives the cooling, cleaner air and protection that urban nature can provide.
The shade of tomorrow is being decided today. And cities cannot afford to wait decades to discover that they removed the very infrastructure they needed most.
