The March sun can put stress on Berlin’s trees
Wed 23/03/22 | 06:06 | Of
After a gray and seemingly endless winter, the sun has finally been shining for a few days. But not everyone is happy with the cloudless sky: nearly a million trees in Berlin’s streets and parks are suffering. By Oda Tischewski
Blue sky over the small Moabit Zoo. The tree branches in the park are still bare, but the tops are slowly turning green and swelling. Spring is about to break out and it is already too dry.
“The first thing the tree does when it sprouts is pump water into the buds, which then get really big. And when the leaves come out, you can only see if the tree is suffering from drought stress,” says Christian Hönig, specialist consultant for tree protection at the BUND Berlin (German Association for the Environment and Nature Conservation): “Whether and how much drought stress it has depends, among other things, on its location. If it is freely in the sun, it could be a glass facade of a building next door, which reflects the sunlight, there is a drainpipe running from the gutter, from which the water comes – you can’t say in general. “
How to tell if trees lack water
The drought of recent years has added to Berlin’s water reserves. And for street trees, the spreading of salt – which ends up in the ground in a slightly diluted form – is an additional burden. Among other things, they react by reducing photosynthesis, which is the energy requirement. As a result, they form smaller and smaller leaves, the crown becomes transparent or rust-red spots on the leaves indicate that the salt concentration is too high. Anyone now looking at the birch or Japanese cordon in front of the balcony may be wondering: do they need my help now?
“Drought stress is best recognized at the top of the tree, when the tree starts to have fewer leaves, which are smaller and lighter, curl up and over time affects the entire tree,” explains Christian Hönig. Eight to ten buckets of water once a week – that should be that much if you really want to do something good for the tree. “The soil must be properly moistened,” says Christian Hönig, “because the problem with street trees is that they already have shallow roots. Insufficient water is therefore more likely to cause damage.”
How to help trees on your way
If you now want to take care of the tree in front of your window, you can first find out more on the Internet, for example on the page “Gieß den Kiez”. [externer Link]. The initiative has drawn up a map on which most of the trees in public areas in Berlin are marked, with their species, age and water requirements.
“More than 2,000 active castors across Berlin have adopted over 5,000 trees using the app and have already poured 780,000 liters of water – that’s a lot!”, Says Julia Zimmermann, who works as a research assistant at “Gieß den Kiez”. As a result, a chat feature has been set up that anyone can join. “We observe that local residents exchange information about who poured where, where a pump failed or something similar. We would like the administration to use it and activities to be coordinated,” says Zimmermann. It is useless if the park office irrigates one day and the residents do it again the next day. “It’s not healthy for the tree. You can even water too much!”
BUND asks for help for street trees at the beginning of the budding phase
The Berliner BUND has long been calling for a “spring service” for the trees on the streets of Berlin, a kind of extra care unit with fertilizer and water at the beginning of the budding phase, explains Christian Hönig. “This would give the trees a good start to the year.”
Broadcast: Evening Show, March 23, 2022, 7:30 pm