Consequences of climate change – City of Zurich plants more trees from the Balkans after a storm – News
After severe snow and storm damage, the city of Zurich is replacing fallen trees with more robust varieties from abroad.
On the night of July 13, 2021, storm “Bernd” swept over Switzerland, and it raged most violently in the city of Zurich. The trees buckled in rows. That night alone, the storm cleared 14,000 square meters of wood in the city forest. As much as the city usually falls within the framework of the management in a year. 19,000 trees damaged in parks and streets, 2000 of them so severe that they were felled in an emergency or were felled.
We’re still processing the pain.
A total of 30 percent of the city trees were damaged. Not only because of the storm, in January it had already suffered a heavy load of snow.
Overall, the city expects costs of ten million Swiss francs for clean-up work and reforestation. It will be 2025 by the time all trees in the city are replaced.
“We are still processing the pain,” says Christine Bräm, director of Grün Stadt Zürich. “But things are slowly picking up again.” In the forests, the gaps are to be closed again through natural growth. In the city, dying trees are being replaced and even more trees are to be planted. “Trees are the best way to reduce the heat,” says Bräm. A measure that was already a done deal before the heavy snowfall in January and storm “Bernd”.
Even so, the city cannot simply go back to normal after the damage caused by snow and storms. Until now, Green City of Zurich has always relied on native tree species, but this will change in the years to come. Trees from southern and southeastern Europe are to be planted more often in the future, says Bräm.
Because in the last few years it has become hotter and drier in the streets. A Norway maple used to survive this well, now it no longer grows properly. Now you have to take care of trees that could grow: “We have to choose the right trees for the future, heat and drought die. Trees that can withstand heat and drought.” Often these are varieties from the Balkan region.
A Norway maple no longer grows properly today.
New technologies such as laser scans are also used to measure how young urban trees are coping with the conditions and how they are developing. “After four years you can already see big differences where they have grown well and where they have grown less well,” explains Christine Bräm.
Which tree species are sustainable?
To find out which tree species can withstand the more frequent dry seasons, the Federal Office for the Environment, the Federal Research Institute for Forests, Snow and Landscape, 20 cantonal forest departments and several forest owners are jointly carrying out a project. To do this, they plant over 50,000 young trees. These will include native species such as fir, larch, oak and winter linden. But also species from warm and dry regions such as the hazel tree, the atlas cedar or the Douglas fir.
Several trees are planted in the canton of Valais, as the Valais is particularly affected by climate change. Over the next 30 to 50 years, they will check how trees develop. The first results are expected in five years.
Tidying up and replanting is a «Herculean task», so the director of Grün Stadt Zürich. SHE WILL WORK THE CITY FOR SEVERAL YEARS.
200 new hardy young trees per year
Other cities also worry about the future of their trees. In Bern, for example, records are kept of exactly where and how many trees are. There are 21,000 on public property, two thirds of them in parks or along the Aare, and one third in the street. On a map it describes exactly where which tree species is located.
In the Swiss settlement area, the proportion has quickly fallen by 10 percent over the past two decades. The city of Bern has grown by 18 percent, writes the city of Bern. Through vandalism, dog urine, floor vibrations or construction work whenever sick trees are felled over and over again. On average, 200 new, resilient young trees are planted every year.