They provide shade, are lovely to look at and ecologically valuable. Millions of avenue trees line Germany’s streets. But many avenues have already disappeared.
Eberswalde/Schwerin – avenues and street tree rows are loved and feared. Loved for their beautiful appearance, because they provide shade, are ecologically valuable and structure the landscape. Feared because roadside trees can be deadly obstacles to motorists and motorcyclists who veer off the road.
The tree-lined street trend is more than 200 years old. The systematic planting of avenues along the roads in Germany began at the end of the 18th century, mainly in Prussia, says Jürgen Peters of the Eberswalde University for Sustainable Development ahead of the avenue day on October 20. At that time, new highways were planted with trees, which were offset about one meter left and right at a distance of ten meters next to the road. At first it was often poplar, later mainly oak, linden and elm.
Trees as delineators
“The tree was the delineator so that you could see the road clearly even in winter,” says the professor of landscape planning and regional development. In the case of the water-bound road surfaces made of clay, shading also played an important role – to prevent excessive dust development and to provide shade for people and draft animals.
According to current studies, there are around 20,000 kilometers of avenues in Germany – with a focus on the northern half and especially in the east. The signposted Deutsche Alleenstraße leads through parts of the country. There are also around 70,000 kilometers of one-sided rows of trees. “My thesis is that many rows of trees used to be avenues,” says Peters. When the road was widened, a row of trees along the avenue was often felled. Today the linden is the dominant avenue tree. Maple is also strongly represented.
Peters sees a problem in the dominance of the lime tree. “This entails the risk that, like the elm bark beetle 100 years ago, we will eventually have a calamity that will cause the lime tree population to collapse.” Even if the lime tree is relatively resistant to drought and heat, it would be good to diversify with a view to climate change. The Spanish oak or the sweet chestnut would be suitable, for example, as well as the black locust in particularly dry locations, says Peters.
Obstacles to replanting
According to Peter, there are often obstacles when replanting avenue trees. The ESAB guideline for federal and state roads to protect against impact with trees is a problem because several meters distance to the road should be maintained. But there is often arable land that the farmers do not want to make available. “That’s why there is hardly any replanting.”
The consultant for tree and avenue protection of the BUND Mecklenburg-Vorpommern, Katharina Dujesiefken, refers to the great loss of avenues in recent years. In 2006 it was still 27,500 kilometers. The densest network of avenues can be found today in Brandenburg and Mecklenburg-West Pomerania. They are particularly rare in Hesse, Bavaria, Baden-Württemberg and Saarland.
From Dujesiefken’s point of view, the ESAB guideline should not actually be an obstacle to replanting in the existing row of trees. According to a circular from the Federal Minister of Transport from 2017, this is allowed. “Hardly any road construction administration makes use of this opportunity – unfortunately.” According to Dujesiefken, the guideline (RPS 2009) for passive protection on roads by vehicle restraint systems (e.g. crash barriers) are also responsible for the sharp decline in new plantings and the increase in felling. responsible.
The protection of the avenues is even stipulated in the Federal Nature Conservation Act. Only in Mecklenburg-Western Pomerania are avenues protected in the state constitution. Dujesiefken calls for a rethinking of traffic safety: “Caution and responsibility of the individual must come to the fore”.
which endangers growth
Dujesiefken agrees with Peters in calling for more tree species diversity in Allen. “This is the only way we can, for example, prevent a total failure in certain road sections and limit the pressure of pest infestation.” Street trees often have difficult conditions. The keywords are cutting measures in the crown, damage caused by accidents, work in the root area, de-icing salt in winter, pests and diseases as well as longer and longer dry periods. “This makes it difficult for new plantings to thrive, and even old trees can hardly find any groundwater.” dpa
