The heat of the past few days shows unmistakably that there is an urgent need to cool our cities.

The best way to achieve this is through greenery, especially trees.

In Bavaria, of all places, where trees were sometimes even hugged by the prime minister, things don't look good there.

This was the result of a survey by BUND Naturschutz (BN) in the 15 largest cities in Bavaria.

Timo Frasch

Political correspondent in Munich.

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According to this, at least 165,000 trees have been felled in the past ten years.

If you compare this with the subsequent plantings, there remains a minus of at least 34,560 trees.

Since some of the cities only provided very incomplete data, the actual numbers are probably significantly higher, according to the BN.

He also pointed out that just under 100 of the 2,056 Bavarian towns and communities had a tree protection ordinance.

These, in turn, usually only included trees of a certain thickness - trees that have not yet reached this could be felled without it being noted anywhere.

"The result of our survey is shocking," said BN chairman Richard Mergner at the presentation.

Trees grow slowly in the city

Replanting would be difficult to compensate for the loss of an old tree.

A lime tree, for example, grows 25 to a maximum of 50 centimeters a year.

It takes an average of 25 years for a newly planted linden tree to reach an average size of ten metres.

"In the city, the trees usually only grow a few centimeters a year because they don't have enough space to develop from the root system," says Mergner.

The BN measured the temperature in several places in Munich on Wednesday using an Aßmann aspiration psychrometer.

This allows the true temperature, not falsified by solar radiation, to be determined.

The temperature at the treeless Marienplatz was 35.1 degrees, in the English Garden 32.1 degrees.

A net 21,600 trees have been lost in the state capital in the past ten years.

"Green spaces and trees play an important role in the air conditioning of a city," said BN tree specialist Christopher Busch.

"A mature deciduous tree easily evaporates 400 liters of water on a hot summer's day and thus cools down its surroundings.

A deciduous tree with a crown diameter of 15 meters also cools an area of ​​at least 170 square meters with its shade, depending on the position of the sun.”