Weather: why are the trees already starting to lose their leaves?

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Colchiques in the meadows, it’s the end of summer… Despite still very summery weather over most of France, the season is indeed coming to an end and September 1, 2022 will mark the beginning of autumn meteorological.

In the street, the tone is set by the tree leaves that already litter the sidewalks, giving us the impression of strolling in the middle of November.

How do you explain that the trees are already losing their leaves at this time of year? Should we see an early autumn or, on the contrary, a particularly hot and dry summer?

It’s answer B, says Régis Crépet, meteorologist for La Chaîne Météo. “It has nothing to do with autumn, it’s a direct effect of the drought,” adds the specialist. The summer of 2022 is precisely the second hottest summer since records began in 1900, after the historic summer of 2003.

To what do we owe this phenomenon? In reality, nature protects itself from bad weather by putting itself “on standby”, explains Régis Crépet.

“It’s a natural reflex (…) we call it water stress: due to the lack of precipitation and humidity, the trees no longer have water to make the sap rise in the trunk and feed the leaves. , irrigate them”, articulates the forecaster. “The sap remains concentrated in the trunk to prevent it from dying,” he continues.

In short, the tree can no longer draw water from the ground and therefore “falls asleep”, thus depriving the leaves which will wither, turn yellow, then fall to the rhythm of the winds.

In autumn, the leaves fall because the days are getting shorter and the cold is felt: no link, therefore, with the bareness of the trees in recent weeks.