Experts hope to make Prague trees do more for city


More than a hundred thousand trees stand in the streets of Prague, working as natural air-conditioning during heatwaves, but many of them have been withering as a result of climate change and unsuitable conditions. Experts are working on new guidelines that would improve the situation.

Thursday is yet another day when temperatures in Prague are well into the 30s Celsius, making the streets, especially in densely populated areas, unbearably hot and unhospitable.

Climate experts have long agreed that the cheapest and most effective method of cooling down streets is planting trees. Apart from reducing temperatures, they can also provide shade and help clean the air.

Jan Richtr | Photo: Jan Malý,  IPR Praha

Jan Richtr is a landscape ecologist and co-author of the new “tree manual”, drafted by the Prague City Planning and Development Institute:

“Trees are hugely effective biological air conditioners. They need a flow of water from the ground into the canopy to bring nutrients to the leaves, so they can photosynthesize properly. And then they have to get rid of that water by evaporation.

“We call it transpiration of plants. The trees are basically cooling themselves, which also cools their surroundings. This is the primary service that we expect and need from trees.”

At the moment, there are around 100,000 trees lining the streets of Prague, but recent heatwaves have shown that some of the previously popular varieties are no longer suitable.

David Hora | Photo: Karolína Vránková,  Czech Radio

One such example is a 40-year-old silver linden growing on Vinohradská Street in the centre of Prague, as arborist David Hora from the Prague City Planning and Development Institute showed Czech Radio:

“You can see that the deep green leaves are wilting and turning brown. This species turns out to be less tolerant of temperature and moisture fluctuations than, for example, the native species of the small-leaved lime and big-leaved lime, which were previously thought to be less suitable.”

In addition to weather fluctuations, the impacts of climate change also make the trees more susceptible to pathogens that spread around the world as a result of globalisation.

To make the trees more resilient, there must be a much more diverse spectrum of species, says Mr. Hora. One of the new varieties, which have proven to be very successful, are pagoda trees, native to Asia:

Prague | Photo: Miloš Turek,  Radio Prague International

“You can see that these trees look quite green and vital, despite the weather. The reason why they thrive even in the paved, seemingly inhospitable area, is that we have a structure built underground that carries the weight of the pavement, with loose soil underneath. These trees were planted here four years ago and during that time the volume of their trunks and crowns have already doubled.”

The Prague City Planning and Development Institute is currently compiling a database of trees in the city. At the same time, a project is underway testing out new, exotic species.

In addition to that, Prague City Hall is working on fulfilling the goal adopted in 2019 of planting a million new trees on its territory by 2027.

Prague | Photo: Miloš Turek,  Radio Prague International