On paper, the development of these two hectares will ultimately create a true “forest environment”. Wedged between the first kilometers of the A43, a commercial activity zone and agricultural land, the “urban forest” of the Horse Post Office (named after the locality) remains inaccessible other than by car. The place was not designed as a park for the Sunday stroll but to promote the return of pollinating insects and other animals of all kinds.
It was a flagship promise of environmentalists during the municipal and metropolitan elections of 2020. “We will create urban forests of 3 to 5 hectares (…), even in the heart of Part-Dieu! », Hammered the program of Grégory Doucet and Bruno Bernard. And since ? At the end of our investigation, it is clear that the major ambitions formulated during the election period have been revised downwards.
Admittedly, “urban forests” are at the center of the Metropolis’ revegetation policy. According to the Nature plan presented in June 2021 by Bruno Bernard, they must “increase the supply of freshness, create biodiversity refuges and improve the landscape quality of streets and public spaces”. But for many of them [voir notre carte ci-dessous], no planting date is planned, one year and three months after the start of the mandate. This is the case for projects in Gerland, in the 8e district or on the Part-Dieu side, all mentioned in the professions of faith of former environmental candidates.
For the moment, apart from the plantations at La Confluence, started in 2019, the rare “forests” to emerge from the ground remain confined to peri-urban sectors such as that of the Horse Post office, in Saint-Priest, or that of the Zac. Castellane, in Sathonay-Camp, where the Metropolis created an arboretum, also in March. And the scale of these projects is below the promise of afforestation of “3 to 5 hectares”: two hectares for “the forest” of Saint-Priest, 1400 square meters for the hundred trees of Sathonay-Camp.
“We have undoubtedly used the term” forest “a little naively”
A revealing sign, the very expression of “urban forests” has sometimes been abandoned over the months in favor of “urban afforestation”, as for the project of the rue du Docteur Bouchut,
at Part-Dieu. “We have no doubt used the term ‘forest’ a little naively. We cannot speak of an “urban forest” for spaces that are between 500 and 1000 square meters. It’s far too restricted, ”recognizes Nicolas Husson, deputy mayor of Lyon in charge of nature in the city. The chosen one refutes the idea of a renunciation, he prefers to speak of a “rectification” …
The semantic evolution reflects a principle of reality: in the densest sectors of the Lyon metropolitan area, city and metropolitan areas are struggling to free up space and have the land needed for XXL revegetation. According to the National Forest Inventory (which depends on the Ministries of Agriculture and Ecological Transition) a wooded area must occupy a minimum area of 5,000 square meters (or 0.5 hectares) to be qualified as a “forest”. . The objective of vegetating rue Bouchut remains unchanged, underlines for example Nicolas Husson, but “the word afforestation is now preferred for the sake of intellectual honesty”. That is. Still, the honorable fine arrives a little late while in 2020 Grégory Doucet campaigned on this Part-Dieu “forest”…
The speech is the same on the side of the Metropolis where the Deputy Vice-President for the Environment, Pierre Athanaze, seems concerned. “We may have played a little bit on words and that is why I suggested to President Bruno Bernard that we clearly define what an” urban forest “is,” he confides. A laudable intention to tune the ecological violins. Example: to qualify the plantation carried out on the Mue Station site in Confluence, Nicolas Husson speaks of an “urban forest”, unlike his colleague from Greater Lyon. “I’m not going to tell you that what we did at La Confluence is an ‘urban forest’. No, we simply planted to fight against a heat island, ”considers Pierre Athanaze.
An official definition
This seemingly superficial debate reveals above all how difficult it is to define what an “urban forest” is. Annabel Porté, researcher in forest ecology at INRAE in Bordeaux (National Research Institute for Agriculture, Food and the Environment), notes that the use of the expressions “urban forests” and “micro-forests” s ‘has intensified in recent years without meeting the true definition. “The designation” urban forest “was registered by the FAO [l’Organisation des Nations unies pour l’alimentation] to designate not a plantation but the set of all the trees present in an urban fabric, she notes. The “urban forest” of Lyon is all the plant tissue made up of alignment trees, park trees… spread throughout the city. “
Trees, trees, trees … During the municipal and metropolitan elections of 2020, the candidates all promised to extend the canopy of the city. But what about today? Inventory in pictures (often spectacular!) ⤵️https://t.co/Ex75sngNyU
– Mediacités Lyon (@MediacitesLyon) August 25, 2021
How to distinguish “urban forests”, in the sense of elected ecologists from Lyon, from simple parks or squares? “Our objective is to establish true forest environments in the city, not to plant a few trees in a landscaped park. Visitors will find a forest atmosphere, ”answers Pierre Athanaze. These “urban forests”, or rather “urban afforestation”, would also be distinguished by the benefits they would bring to the territory, continues the vice-president of the Metropolis: cooling thanks to the shade of the foliage and to the evapotranspiration [un phénomène naturel de transpiration des végétaux], protect biodiversity in the city, encourage the return of bees …
According to Nicolas Husson, the density of plantations can increase their benefits. The one carried out by the city of Lyon in Confluence thus experiments with the concept of “Miyawaki forest”. This technique, which owes its name to a Japanese botanist, consists of planting a variety of species very densely in order to induce rapid tree growth and “renature the soil”, in the words of Grégory Doucet’s assistant.
But researcher Annabel Porté calls for caution. “For about five years this technique has experienced a resurgence in popularity and many micro-forests have been planted in this way,” she observes. The problem is that no scientific study has yet demonstrated their impact on the biodiversity of the surroundings. “According to her, the” Miyawaki forests “would present a major drawback:” Since we end up with 300 trees per hundred square meters, very quickly the plants run out of space. A natural process of self-thinning takes place. That is to say that some individuals die which allows others to grow. In these plantations, the mortality is therefore very high. “
This method of dense planting of young trees in urban spaces is very popular in France. It has its followers and its detractors. But what is it really worth? https://t.co/Cnz6YrCle4
— The Conversation France (@FR_Conversation) March 16, 2021
However, all the trees of these “urban forests” are generally counted by the communities when it comes to communicating on the objectives of the revegetation of the city. Nicolas Husson readily acknowledges this: “Our majority is committed to planting in Greater Lyon 300,000 trees
by 2030. Some of them are in Miyawaki forest and will not all survive, but in the long term the balance will be very positive. ”
Aware of these limits, Pierre Athanaze specifies that the Metropolis is “experimenting” with different planting techniques and seeking to “adapt them to the Lyon climate”. “We are trying to include these plantations in a vast project to strengthen ecological continuity,” he adds. For example, the forest of Saint-Priest is a step leading to the restoration of the biodiversity corridor between the park of Parilly and the large park of Miribel. “
Control of land
To establish an “urban forest”, Greater Lyon selects the site according to two criteria. The first: to ensure that afforestation finds its place in an ecological corridor. The second: to ensure that it will bring a bit of nature to areas that lack it today, such as 8e district of Lyon. Provided, of course, that there is space …
Take the Mandela Esplanade, east of Part-Dieu station. “We have planned to plant in this park, but there are many uses around, with the passage of the tram which complicates things, develops Nicolas Husson. It will therefore be a question of a limited afforestation north of the esplanade since the space is not immense. »In Gerland, the city comes up against the problem of land control. Environmentalists would like to transform the site of the former Nexans factory into “urban afforestation”, but this is counting without the price of the land held by Bouygues Immobilier. Nicolas Husson does not commit to this project, but ensures that “the reflection remains open”. On the 44 million euros allocated to the development of the Nature Plan until 2026, “approximately nine million euros will be dedicated to the purchase of land”, according to Pierre Athanaze.
“While the price per square meter is already so high in Lyon, these plantations risk preventing the construction of new housing or offices”, worries Emilie Prost, metropolitan councilor of the Progressives and Republicans group (that of David Kimelfeld). “This could force households to move out of the way, and therefore to increase the number of trips, especially by car. Finally, these “urban forests” could have negative consequences on our environment, ”she continues, adding that she supports all“ initiatives that can improve air quality ”.
In terms of revegetation, the Balmes de Fourvière project should also mark the mandate of the Greens. Often presented as the future “second lung of Lyon” after the Tête d’Or park, the reunion of parks and squares already existing on the hill will be specified “in a few months”, loose Nicolas Husson. “It will be a real continuity of 80 hectares, from the Jardin des Curiosités to Vaise, going down to Saint-Jean cathedral,” he describes. Except that… The town hall must still ensure the availability of certain land such as a land reserve near the Loyasse cemetery to carry out this work. For “urban forests” like the Balmes, the ambitions of the majority are still subject to conditions, whether they were the electoral promises made in 2020 …
–
