This summer ended with the death of the ficus of San Jacinto, in Seville, a 111-year-old specimen declared an Asset of Cultural Interest. Although the massive felling ordered by the parish of San Jacinto was stopped in 2022 by the Contentious-Administrative Court, the tree did not survive.
One of the main arguments in favour of its felling was the safety of the population, faced with a 24-metre-long tree in the middle of the city. The case has become a symbol of the mistreatment of urban trees.
However, healthy trees in cities are essential for lowering summer temperatures, reducing the heat island effect and providing shade, among other benefits. We asked some of the best tree experts what it takes for cities to have these climate refuges, that is, good shade. The answer is: very large specimens, like the Seville ficus, several years old.
Botanist Bernabé Moya, a scholar and defender of monumental trees, assures that it is above all a question of respecting the nature of each specimen. “Cities must be designed to accommodate trees, respecting their biology and their growth pattern, the space they need above and below ground,” he explains.
Seeing the stunted trees that line many streets, barely surviving in a one-square-metre pit, it is difficult to imagine the dimensions some of these species could reach if allowed to grow.
The city is a hostile environment for trees and plants, because they are designed and thought of according to other coordinates which are not those of nature.
Francisco Bergua
— municipal authority responsible for Parks and Gardens of Zaragoza.
Mariano Sánchez, from the Royal Botanical Garden, gives as an example a plane tree, one of the most common trees on the streets due to its ability to withstand pruning and other hostilities. In an urban environment, a specimen could rise about 10 floors – 30 meters high – with a leafy crown 25 meters in diameter. Two people would have a hard time surrounding its trunk, although the most impressive thing is perhaps underneath: its roots would reach a meter and a half or two meters deep, and would cover the same surface as the crown or even a third more, to stay in place and seek the nutrients and water that the tree needs. The problem is that neither the tree pits nor the streets are designed with this giant potential in mind. “If you plant a banana tree every four meters, it’s like putting Marc Gasol in a tent. “You are killing him,” says Sánchez, who is also president of the Spanish Arboriculture Association.
“The city is a hostile environment for trees and plants, because they are designed and thought in other coordinates that are not those of nature,” explains Francisco Bergua, municipal director of Parks and Gardens of Zaragoza. “In the consolidated city, the urban layouts of the old town, with its very narrow streets and its small typical square, present obvious space limitations,” explains Bergua.
“In addition, in urban areas we have many underground pipes: water, gas, sanitation, vacuum tubes for optical fibers…” In these spaces, says Bergua, you have to think “of a tailor-made suit”. “Not everything has to be a tree with a large crown. Maybe, in the space that there is in this small street or this square, a small or medium-sized tree, or a shrub or another type of plant, contributes a lot”, defends the manager. But in new urban developments, a blank canvas where a real naturalized city could be designed, the situation is not very different, since no thought is given to the development or needs of the tree.
“Generally speaking, the designer, architect or civil engineer, really sees trees as little drawings that look great on paper,” Bergua explains. “In Spain and in many cities in Europe, trees are disposable. You can mistreat them as you like, after 20 years you cut them down and put another one in. You have to ask urban planners when they are going to design cities so that trees can grow for 100 years,” defends Bernabé Moya. To discover what they might look like if they did grow, Moya recommends visiting the botanical gardens and admiring the shady plane trees of Gijón or the majestic oaks of Valencia. But there are also giants that have survived in the streets, such as the immense century-old ficus trees that cover the Alameda Principal in Málaga under a green roof, some of them over 150 years old.
In Spain and many cities in Europe, trees are disposable. You can mistreat it as you wish, after 20 years you cut it down and put another one. Ask urban planners when they will design cities so that trees can grow for 100 years
Bernabé Moya
— Botanist, expert in monumental trees
Against this potential, the average lifespan of trees in European cities is only 30 years, explains the communications director of the Biocities Centre of the European Forest Institute, Livia Podesta. “The problem is neglect and lack of proper maintenance and management, with all the loss of benefits that this implies.”
To destroy an urban tree, it is not necessary to cut it down; a poorly done pruning that rots part of the trunk or roots torn out when raising a sidewalk can also condemn it. Imperceptible damage that is revealed with every gust of wind and every storm, such as the botanical massacre caused by storm Filomena, which covered a large part of the Iberian Peninsula in a white blanket in January 2021. In Madrid’s parks, almost a third of the trees – a total of 269,166 specimens – were damaged, including one in five in the streets of the capital, according to the assessment carried out by the city council.
People are afraid and it has been decided that small trees are safe. But big trees, if you have taken good care of them, are not either. If you have crushed them with the chainsaw, there would be a risk in the future
Mariano Sanchez
— Head of the Arboriculture Unit at the Royal Botanical Garden-CSIC
Fear of fallen trees or broken branches is another reason why there are fewer mature trees in cities, according to Mariano Sánchez. “People are afraid and it has been decided that small trees are safe. But large trees, if you have taken good care of them, are not either. If you crushed them with a chainsaw, there would be a risk in the future,” defends the arboriculturist.
No canopies or chestnut trees for increasingly hot summers
In addition to extreme events like Filomena, another growing threat to urban trees is rising temperatures and more frequent droughts caused by climate change. In the countryside, countless trees are already dying of thirst and heat. In Catalonia, in 2023, up to 66,482 hectares of forests lost their leaves, dried out or died due to drought, a historic record according to the archives of the Centre for Ecological Research and Forestry Applications (CREAF).
“Survival could be reduced in the coming decades. We need to think more about which species will survive best in the future climates of different cities,” says Alison Munson.
At the Botanical Garden of Madrid, Sánchez explains that maples – a species typical of cool and humid places – no longer resist the heat and the drop in humidity in the environment. Another example is the horse chestnut, “a species that should no longer be planted in the continental climate, because it will not last”. The Spanish Association of Arboriculture is collecting species that can withstand climate change. If the future climate of Madrid is like that of Marrakech, it will be a matter of seeing what can last there and applying the lesson.
The most important thing is to learn more about trees and to respect them so that they can continue to make our cities more liveable, contaminating us with what Bernabé Moya calls “botanical culture”. “People ask for a tree that has no roots, that doesn’t grow, that doesn’t lose its leaves because it makes a mess. You ask me for a plastic tree. The fashion is now to install awnings in cities… Can we compare the advantages of a tree with those of an awning,” Moya reflects.
