It is not yet the month of October and yet, the leaves of the trees already display an orange color or fall to the ground. In a publication posted on X, the agroclimatologist Serge Zaka shared aerial images of French forests on Friday, whose trees are partly orange and brown.
The aerial images of many French forests offer us an implacable lesson on the limits of plant adaptation in the face of climate change. From Périgord to the Southern Alps, from the Pyrenees to the Massif Central to Poitou, the clichés flock from all sides. The… https://t.co/44drdjpbs5 pic.twitter.com/flPok4OQKA
– Dr. Serge you (Dr. Zagge) (@sorozaka) August 15, 2025
A phenomenon that is not new: it has also regularly occurred in France – and it is more and more frequent. And for good reason, heat and drought are the main responsible for this change.
Water stress
In another post on the social network, Serge Zaka explains that “our temperate ecosystems are not made for these extreme temperatures. Each summer, with repeated hot blows, they lose their vigor. Some dumb. »»
The expert continues by indicating that “the leaves are burned by a week of thermal records. “According to the agroclimatologist,” the trees are offset from their foliage to limit evapotranspiration (The process by which earthly liquid water is returned to the surrounding atmosphere in gaseous form): Water is missing to keep everything alive. »»
On its website, the city of Paris indicates that “more than high temperatures, this trend is linked to the lack of water in the ground, in particular water stress, which induces dryness and early fall of the leaves. »»
According to the ONF, we can talk about water stress when the lack of precipitation extends and “that the water tank is only filled 40 % or less”.
“The trees could not sweat enough to cool their leaves, which are like burned and therefore fell,” continues Béatrice Rizzo, the service of the tree and the woods of the city of Paris.
Weakened, the tree is less able to defend itself against insects and diseases.
“The state of the tablecloths deteriorates slowly”
Serge Zaka alerts the upcoming situation and estimates that “France at + 4 ° C (current trajectory) would be a France with tattered ecosystems”.
For the time being, the July rains have had little impact on the groundwater and the emptying continues, notes the office of geological and mining research, in a press release published on August 8. “The state of the tablecloths degrades slowly and remains heterogeneous, from very low to moderately high. »»
On the temperature side, the heat wave will last until the end of the day this Saturday before regressing from the North and the West on Sunday and especially Monday. New thunderstorms, early next week, should lower temperatures according to Météo France and put an end to this long scorching episode.
