The carpet of dead leaves crunches underfoot and twirls in a brown cloud, covering the edge of the alleys of Buttes-Chaumont, the “green lung” in the east of Paris, giving it a false air of autumn. But it’s the height of summer, and that day it’s 36°C.
Since mid-July, the trees of the French capital have lived, as in other territories of France, an early autumn caused by repeated heat waves and drought.
And with a month ahead of schedule, the plane trees and the chestnut trees are the first leafy trees to have lost their leaves.
At the foot of a chestnut tree in the Parisian park with rarefied and withered leaves, Tim Peiger, 28, lumberjack for the Department of Green Spaces and the Environment (Deve) in Paris, grimaces. “The foliage should be nice green. ” The ace. “The branches fall back with the weight of the leaves. And when the leaves fall, there is no more photosynthesis, the wood is no longer nourished, it dries out and forms dead wood,” analyzes Mr. Peiger.
However, this spectacular phenomenon linked to the drought remains without gravity at this stage, according to experts from the City of Paris.
“These trees are far from stupid, […] they simply put themselves in survival mode ”, getting rid of their greenery to save their reserves, assures Béatrice Rizzo, member of the Deve.
If the weather conditions are favorable, these trees dried in the summer “can restart a shoot” before the fall, assures Ms. Rizzo.
Plane trees of Napoleon III
But other pathologies, linked to extreme heat, worry him such as “sunburn”, these sunburns on the bark, which dig a wound in the wood and will facilitate its parasitization, threatening the tree in the long term. .
“It’s new and it’s linked to the climate”, underlines the expert.
When the “great gardener” of Napoleon III’s Paris, Adolphe Alphand, set about building the capital’s parks and gardens in the 1860s, creating almost ex nihilo the Bois de Boulogne (west of Paris), Vincennes (east ), the Buttes-Chaumont and the main green “alignments” of the avenues, native species are essential, in particular the plane tree, reputed to be both robust and shady.
“It’s an essence […] which resists drought well and then it is emblematic of the city of Paris”, says the young woodcutter from Buttes-Chaumont about the plane tree, which makes up 38% of street plantations and borders the avenue des Champs- Elysees.
The fact remains that with an average temperature which has increased by 2.3°, against 1° worldwide, according to the Paris Climate Agency, between the periods 1873-1902 and 2000-2019, the town hall now favors new species called Mediterranean, such as the hackberry from Provence and the pine, among the 170,000 future plantations.
New maintenance routine
With these new climatic conditions, the gardeners of Paris have also adapted their maintenance routine.
Despite the water restrictions, “there is no longer a place that we do not water”, explains Irène Henriques, the head of the municipal gardeners at Buttes-Chaumont. His team is thus finalizing on an application the programming of automatic watering at night, recommended by the town hall.
The practice of “size” has also been modified. “We prune less, but more regularly to keep more branches”, informs the gardener.
Mulching, a technique that consists of laying a carpet made up of crushed branches at the feet of the trees to limit evaporation, is preferred.
Surveillance, at the foot and at the top, to identify burns and branches ready to give way is reinforced.
And the regulars of the park are getting into it too. Evidenced by the more or less kind words received by the gardeners from the neighborhood citizen lookouts.
“Today, we don’t yet notice any dramatic things”, admits Daniel Ollivier, 78, at the head of a group of Nordic walking hikers, not very panicked by the early autumn.
“But that doesn’t mean it can’t come very soon,” he concludes, pointing his walking stick skyward.