Sunscreen for trunks Why are trees on the banks of the Rhine in Beuel painted white?
Beuel · The trunks of beech and hornbeam trees on the Beuel Rhine embankment have been painted. Many passers-by are now wondering why this is happening. The white paint can also be seen on other trees in Bonn. Here’s what this is all about.
Is a completely new and hitherto unknown tree species growing there unnoticed in Bonn? Are the stands suffering from pests or a fungal infestation? But maybe it's just to spoil the appetite of hungry game for fresh bark. The trees with the conspicuously white trunks on the Rhine embankment in Beuel have caused a lot of excitement and discussion on the internet in recent days. "Does anyone know what this is all about?" asked a Facebook user who had been observing this phenomenon for some time on his bicycle tour.
An enquiry by the GA at the press office provides the explanation. "The paint is trunk protection paint - sunscreen for the trunks, so to speak, so that the trees can survive the next hot summer," Andrea Schulte explains. This sunscreen is applied to the lower part of the trunks. This would protect the sensitive growth cells from harmful radiation.
Paint is biologically and ecologically completely harmless
According to the city, it does not rely on chemicals. "The paint is biologically and ecologically completely harmless. Over the years, the paint fades until it has completely disappeared," adds Andrea Schulte.
"Prophylactically", beech and hornbeam trees on the Rhine dyke were painted with this precautionary measure last autumn, in order to preserve the old and valuable stock. Both tree species are rather thin-barked. As a result, prolonged irradiation can quickly lead to sunburn. In the process, the affected bark cells die and detach from the wood body over time. "This has a lasting effect on the vitality of the trees and offers harmful organisms the opportunity to settle through these entry ports," says the press office staff member.
However, white coatings like the one on the banks of the Rhine in Beuel are not an uncommon sight in Bonn's urban area. The administration usually treats new plantings this way. Since the trees in the nurseries tend to stand closer together and thus the bark is protected from sunlight, it usually has to be protected after planting.
"That old trees receive a protective coating, as was the case last autumn on the Rhine dyke, is rather the exception, but does happen from time to time. For example, when thin-barked trees like the copper beech are suddenly exposed to strong sunlight on the bark after tree felling. This is similar to what happens to people: skin that is not used to the sun gets sunburned more quickly," Schulte continues.
Heat and drought damage
Heat and drought are particularly damaging to the native copper beech. For new plantings, the Department of the Environment and City Greenery is therefore focusing on tree species that can cope well with the changing climatic conditions, such as Norway maple, Zürgelbaum or Hungarian oak.
"The city is guided by the current recommendations of the conference of garden office managers, but is also testing new tree species itself, such as white and flowering ash," Schule replies to a GA enquiry.
(Original text: Gabriele Immenkeppel; Translation: Mareike Graepel)