Urban plane trees largely help refresh the air

During high heat. Similarly, urban plane trees largely contribute to refreshing the air, evaporating the water contained in their leaves. Moreover, Faced with the increase in planned heat waves. Therefore, they play an essential role in preserving the quality of life in town. Similarly, – Urban plane trees largely help

(Keystone-ATS) This is demonstrated by a new study conducted by the Federal Institute for Research on Forest, Snow and Landscape (WSL) and EPFL. Similarly, But the trees also. a priori, have their urban plane trees largely help limits: when the temperature of the leaves exceeds 30 to 35 ° C, photosynthesis is interrupted, because the stomates close to avoid excessive loss of water.

A team of scientists from the two institutions specifically studied the behavior of plane trees under extreme conditions. The results. published on Friday, are surprising: even beyond 39 ° C, the trees continued to evaporate much more water than expected, thus effectively cooling their environment.

In the spring of 2023. Christoph Bachofen, manager of the study, and his team installed measuring devices on eight plane trees in Lancy, in the Geneva suburbs. The sensors recorded the flow of sap in the trunks. which made it possible to deduce the amount of water evaporated and therefore the cooling capacity. This summer, Geneva precisely experienced two waves of heat with record temperatures reaching almost 40 ° C.

Water reserves?

Amazing observation, the trees did not interrupt their flow of urban plane trees largely help water. On the contrary: the more the heat increased. the more this flow intensified, and this despite an extreme dryness of the air.

“We obviously do not yet understand how trees react to extreme conditions,” said Christoph Bachofen, quoted in a press release. His colleagues and assume that water reserves in deep layers of the soil have notably played a role.

The extent of the water flow observed is surprising. raises important questions, according to him: “If the trees react to heat other than what we thought so far, the forecasts concerning their refreshing effect are then inaccurate – and the models used to predict the future distribution of heat in the city lose their reliability”.

Other essences to study

The fact that the trees evaporate a lot of water even by heat wave is good. news for the urban climate. “The days when the temperature exceeds 30 ° C are increasingly frequent,” urban plane trees largely help says Bachofen.

The next important step for research is to determine the efficiency of perspiration of other species exposed to extreme heat. “This would make it possible to formulate recommendations on essences capable of supporting not only air pollution. snow removal salt, but also strong heat,” notes the scientist.