On an increasingly hot Earth, scientists are once again Urban trees are your friend in the heat. a new research It warns that its ability to cool the environment depends more on soil moisture than on the amount of vegetation present in a city.
At first glance, trees in the city natural shelter from the heatHowever, the true cooling effect cannot be obtained from sunshades alone. researchers discovered that Moist soil is an important factor This allows the leaves to release water vapor and reduce temperatures.
This ability is known as Evapotranspirationwill be interrupted when the ground is dry. As a result, the trees stop “breathing” and their climate benefits are reduced. So, Irrigation management appears to be as important a factor as urban design itself.
Experts warn that without sufficient humidity, vegetation can become symbolic – a green landscape that does not fulfill any environmental function. Understanding this water balance is essential for rethinking urban strategies in the face of a sustained increase in heatwaves.
Why soil moisture is the key to cooling cities for trees
The research is Swiss Federal Institute of Technology (ETH Zurich) and ehwag centerthere are various districts zurich. The results were overwhelming. trees By using well-hydrated soil, they were able to significantly reduce ambient temperatures, especially in densely populated streets.
The research revealed that Humidity not only promotes leaf cooling, but also direct evaporation from the soil.The freshness effect is doubled. In areas dominated by pavement, its functionality is almost completely lost.
Researchers say soil requires 2 to 4 liters of water per square meter per day during the summer to maintain optimal conditions. To this end, they recommend: automatic irrigation system Respond to weather forecasts and optimize resource usage.
Shadow and evaporation form an inseparable binomial. The former acts immediately, while the latter creates long-term relief and helps stabilize the city’s microclimate. Together, both can lower local temperatures by up to 3 degrees on cold days. extreme heat.
In cities like Singapore Either melbourneIn , the concept of green and blue infrastructure has already been integrated into urban planning, and the results are visible. Combining vegetation with sustainable drainage and permeable materials not only keeps you cool, but also prevents flooding.
The study authors note that watering more is not necessarily better. a excess moisture It can saturate the soil and prevent root oxygenation. The challenge is to apply light and frequent irrigation to promote penetration and avoid waste.
In the long term, this approach will redefine the way we think about urban trees. Not as a simple landscape element, active climate infrastructure. With proper maintenance, you can reduce air conditioning use and potentially improve public health during the harshest of summers.
The researchers’ final message is clear. Urban trees can be a decisive ally against the heatBut only if there is the necessary humidity for it. Managing water wisely is just as important as planting more greenery.
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