Paris, often cited as one of Europe’s worst cities during heatwaves, faces a pressing need for increased green spaces. With only 14% of its surface wooded (excluding the peripheral Bois de Boulogne and Vincennes), rising to 21% when including them, the French capital remains one of the least forested in Europe. In response, Mayor Anne Hidalgo’s administration, elected in 2020, committed to planting 170,000 trees by 2026, with the creation of four “urban forests” as a flagship initiative. Now, five years into this promise and weeks before the next municipal elections, it’s time to evaluate the reality of these projects.
The “Urban Forests” – Where Are They?
While initial site plans shifted due to technical difficulties, three urban forests have already been inaugurated:
- Place de Catalogne: Opened June 2024, this 1-hectare former traffic roundabout in the 14th arrondissement was entirely mineralized. It has been re-greened over 4,000 m² with 470 trees (16 species) and 1,200 shrubs, achieving a density of 12 trees per 100 m².
- Bois de Charonne: Inaugurated September 2024, this linear site in the 20th arrondissement spans 2 hectares along a former railway line. It features 112 tall trees among 7,500 young saplings (40 species) and 2,200 shrubs (40 species). This new forest adjoins the existing 1.5-hectare “Jardin de la Gare de Charonne.”
- Hôtel-de-Ville Parvis: Opened June 2025, this site comprises two vegetated areas totaling 2,500 m², separated by a central mineral section. It includes 46 mature trees (up to 10m tall) of five species, alongside smaller trees and shrubs.
The fourth site, at Place du Colonel-Fabien (10th and 19th arrondissements), covering 1,460 m² with 79 new trees, is expected to be completed in early 2026.
Are These Truly Forests? A Definition Dilemma
A crucial question arises: do these new green spaces truly qualify as “forests”? According to the Food and Agriculture Organization (FAO), a forest is defined as a land area of at least half a hectare (5,000 m²) with a tree canopy cover of at least 10%. By this definition, most of Paris’s new urban forests, with their varied sizes and densities, may not fully meet the criteria. The Place du Colonel-Fabien site, at 1,460 m², falls significantly short of the FAO’s minimum area.
Serge Muller, a professor emeritus at the National Museum of Natural History (MNHN), points out that these spaces are perhaps closer to urban squares and parks, albeit with denser plantings and smaller recreational areas. The Bois de Charonne, for instance, benefits from its proximity to the 40-year-old “Jardin de la Gare de Charonne.”
Beyond the Green Façade: Naturalness and Native Species
The Parisian urban forests aim for a more “natural” aesthetic, prioritizing indigenous species from the Paris Basin or mainland France over exotic ones. For example, nearly 60% of the trees at Place de Catalogne are native to the Paris Basin. However, this commitment to naturalness doesn’t always extend to shrubs, with 95% of those introduced at Place de Catalogne being two species from East Asia. The herbaceous plants largely consist of a patchwork of fern cultivars.
This raises questions about the long-term ecological benefits. Muller suggests that instead of a heterogeneous mix of floristic origins, a purely sub-Mediterranean assemblage could have been experimented with, to test its adaptation to future climatic conditions. Furthermore, these urban forests differ from the “Miyawaki micro-forests” model, which involves extremely dense plantings of young, exclusively native saplings. Paris’s new mini-forests feature taller trees (several meters high) and lower densities (one to ten trees per 100 m²).
The Value Proposition: What Do These Forests Offer?
Despite these critical observations, the new urban forests undoubtedly contribute to the city’s greening, increasing its canopy cover and ecological connectivity, even if on a modest scale. They represent pilot operations, generating significant media attention and incurring relatively high costs, demonstrating the feasibility and environmental benefits of creating “urban forests” from scratch. Their long-term evolution over the coming decades will be crucial to assess their true impact.
These initiatives, as outlined in the city’s “Tree Plan 2021-2026,” must complement and ideally connect with other planting efforts, such as tree alignments, the creation or expansion of urban parks and squares, and the densification of tree populations in cemeteries, schoolyards, and other open spaces. The overarching goal is to substantially increase canopy cover across Paris and the greater Grand Paris metropolis, better adapting these urban areas to the climate conditions of the coming decades.
A Political Statement or a Genuine Solution?
The creation of these urban forests is more than just an environmental initiative; it’s a political statement. Mayor Hidalgo’s administration has championed these projects as a key part of its strategy to make Paris a greener, more resilient city. However, critics argue that the scale and nature of these projects might be more about optics than substantive change, especially given the strict definition of a “forest” and the city’s overall low tree cover compared to other European capitals.
The timing of the inaugurations, particularly with municipal elections on the horizon, also invites scrutiny. Are these projects genuinely transformative, or are they designed to generate positive headlines and electoral goodwill? The answer likely lies in a combination of both. The intent to green the city is commendable, but the execution and the actual ecological impact warrant closer examination.
Looking Ahead: The Future of Urban Greening in Paris
The success of these urban forests will ultimately depend on their ability to withstand the challenges of climate change, foster biodiversity, and provide tangible benefits to Parisian residents. This requires not only initial planting but also ongoing maintenance, monitoring, and a willingness to adapt strategies based on scientific feedback.
The debate surrounding Paris’s urban forests highlights a broader challenge for rapidly urbanizing areas: how to balance the urgent need for environmental sustainability with the practicalities of urban development, political cycles, and public expectations. While these initial projects may not perfectly align with every definition of a forest, they represent a step towards a greener future for Paris. The critical question remains: is it a bold leap or a tentative shuffle?
Only time, and the continued scrutiny of experts like Serge Muller, will tell whether these “urban forests” truly blossom into the ecological havens Paris desperately needs, or if they remain symbolic gestures in the face of a rapidly changing climate.
Source: https://www.tela-botanica.org/2026/03/quel-bilan-pour-les-nouvelles-forets-urbaines-de-la-ville-de-paris/
