Paris suffocates when the heat crushes it. It would only take another heatwave to remind residents that once the mercury explodes past seasonal norms, their city will turn to a leaden screed. To fight against this urban furnace there are not thirty-six solutions: it is necessary to vegetate. The town hall also shows this ambition with its tree plan presented in December 2021. The goal: to plant 170,000 trees by the end of the mandate. Will Anne Hidalgo’s team live up to their promises? ? reporter re tries to find out, but the answer is far from easy.
Open data: unreliable numbers ?
To follow the evolution of the plantations in Paris, you can consult the Open Data database, regularly updated by the city’s technical services. On the tab “ Surroundings » there is information about islands of freshness, trees to be felled for health reasons, notable trees, community gardens or greening permits. Here is the number of trees in the city: 205,855 as of June 17. For comparison, we found the story thanks to Mathieu, a 5th-century environmental activiste Arrondissement archiving open data since 2020. According to his calculations, there were 205,124 trees in July 2020.
The city would have gained only 731 trees in the past two years. A much lower figure than those communicated in the media, which reported nearly 5,000 trees planted inside the walls. Why such a difference ? Green space and environmental management ensures that the open data database is not updated in real time. “ A count of open data to evaluate inventory of 170,000 [170 000 arbres] Bäume doesn’t rhyme with anything and is dishonest », Write the city services in an email consulted by reporter re. “ We have never planted so much since the mandate began. In the last two years we have planted 38,557 trees. More than 18,000 on the embankments of the ring road. More than 12,000 in the woods. But also more than 4,700 in inner-city Paris »takes care of that a video Christophe Najdovski, deputy mayor of Paris, responsible for the replanting of public spaces, green spaces, biodiversity and animal health.
- Trees were felled at the Porte de Montreuil for a real estate project. © Laury-Anne Cholez/Reporterre
Tangui Le Dantec, architect and urban planner, member of the National Tree Monitoring Group (GNSEA) and co-founder of the collective Aux Arbres Citoyens, also takes open data numbers with a grain of salt. “ When a tree is felled, it disappears into thin air and we start from scratch with a new tree planted. This does not facilitate the task of checking and understanding the development of things. » What will then be the balance sheet of all these operations ? Will there really be more trees in Paris? ? Asked by reporter reChristophe Najdovski does not provide any further details: “ We don’t have a number target, but a quality target. »
The untenable campaign promise of 170,000 trees
Consider the 2019 campaign pledge to plant 170,000 trees over six years in office. Tangui Le Dantec has pulled out his calculator : In order to reach such a number, a total area of 5.7 km² would have to be free, i.e. the area of the 17the District. The goal seems unattainable. “ If we only look at the streets of Paris, we will obviously not be able to plant as many trees due to space constraints, Christophe Najdovski is annoyed on the phone. But on the slopes of the ring road, for example, using the Miyawaki method, these plantations bring benefits? ? We think so. »
The Miyawaki method is a Japanese technique that aims to plant native species very densely in an area of one square meter. Then let nature take its course. This method has been challenged by environmental groups, who question its long-term viability and denounce high mortality rates.
“ We come to force the loggers to plant dead trees »
Because in addition to the quantity of the trees planted, their quality will have to be assessed above all. At France Nature Environnement (FNE), we prefer to think in terms of the crown, i.e. all the branches and leaves that absorb that CO2. “ If you cut down a 30-meter-tall tree with a crown of a hundred cubic meters and replace it with a very small one, it has nothing to do with fighting pollution or global warming. »assures Yves Contassot, councilor of Paris and former environmental assistant.
The lumberjacks of the city of Paris are also noticing a deterioration in the quality of new shoots. Last March, one of the teams was tasked with cutting down ten trees on rue Ordonner on the 18th floore District of Paris: “ They were delivered almost dead. We planted them anyway. Only a month later they were really dead. Our ministry is so disorganized that we have to force the loggers to plant dead trees »says a lumberjack on condition of anonymity.
- Climber and arborist Thomas Brail perched in one of the plane trees near the Eiffel Tower. © Mathieu Genon/Reporterre
Why does felling trees inspire so many passions? ?
Around 3,000 trees are felled in Paris each year for health reasons. But many others are being sacrificed on the altar of real estate expansion. For example, a concrete project for the gardens near the Eiffel Tower threatened 42 trees. To save them, arborist-climber Thomas Brail had set up camp on top of a plane tree and started a hunger strike. “ The project was reviewed with the aim of zero slaughter. It is clear that citizen mobilization around the Eiffel Tower has changed the game »assures Christophe Najdovski.
Also read: In Paris he perches on a tree to warn of the state of the forest
The strong mobilization to defend the plane trees of the Eiffel Tower surprised Mathieu, activist from Europe Écologie-Les Verts (EELV) of 5e District. “ Cutting down a tree is emotional. In a time of plenty it would not be noticed. But today, since there isn’t enough of it in Paris, people see it immediately. » Indeed, the capital of France is far from being a good student in this field. According to figures from the Green View Index Paris only has 8.8 % Plant Cover, compared to 28.8 % for Oslo or 12.7 % for London.
So there is still a lot to be done to bring it up to the level of other European cities. Paris would have everything to gain by accelerating greening projects, as scientific studies have demonstrated the benefits of trees to human health and morale for decades. The first dates back to 1984. Psychologist Roger Ulrich had shown that patients hospitalized after surgery recovered faster and had fewer complications when their window overlooked trees. Other studies show that the presence of trees would increase life expectancy, reduce stress, depression or crime. According to the United Nations (U.N.), trees can reduce up to 30 % air conditioning demand.
Which greening policy for cities ?
Given so much evidence, why hang around and green the streets? ? Why not impose a moratorium on all tree felling, as some environmental organizations are proposing ? Because replanting is good, but avoiding destruction is even better, as Tangui Le Dantec reminds us: “ We’ve seen over the past few years that trees are still an adaptive variable in real estate projects. It is now more than necessary to stop concreting, which increases the thermal inertia of cities. All new construction should only be done on artificial surfaces. Open spaces in the ground should be preserved, for example at the foot of the Eiffel Tower. »
- On this plot of land near Montreuil the trees have been felled to build a real estate project. © Laury-Anne Cholez/Reporterre
In Paris we emphasize so much more
Paris is still a long way from that. Take the example of the Bruneseau project in the 13th centurye District where 29 trees were felled. “ However, building permits were rarely filed and legal challenges resulted in the project being shelved. So why such a rush ? Shouldn’t we keep them as long as possible? », asks Yves Contassot.
Another example, Porte de Montreuil, where 76 trees were felled for a “ urban operation » 60,000m2. Deforestation is to be compensated for by vegetation grated on the plate. “ For some projects, the building permit was granted several years ago and felling was planned, as was the case with the Porte de Montreuil. I couldn’t stop it », promises Christophe Najdovski. The elected official ensures that the future local city plan says “ bioclimatic » will force developers to design their real estate programs with existing trees in mind. “ There is a shift on this issue that didn’t exist three years ago. We now have a general awareness of the need to conserve and the economic value of trees. »
But in the face of all these political promises, Tangui Le Dantec remains skeptical: “ Heat waves will increase. It is now more than necessary to pursue a serious, rational and scientific policy. Cities like Paris are a matter of life and death. Unfortunately, I fear that nothing will change until we face a situation at least as dramatic as August 2003. »