Welzow (Germany) (AFP)
A silent killer of a few millimeters: the bark beetle, a kind of mini-beetle, plunders the German forests weakened by drought and storms linked to global warming.
If this little beetle "creates problems for 200 years", says Dr. Peter Biedermann, University of Würzburg, it ravages in recent years trees "in water stress", a topic at the heart of a government summit Wednesday .
Skeletons of gray-brown trees, without leaves or thorns, are gradually replacing green and healthy hardwoods. In the forest of Welzow, about a hundred kilometers south of Berlin, the damage of the bark beetle and its larvae is visible to the naked eye.
Inside the trunks of dead trees, small galleries are dug, sign of a recent passage.
"The insect gnaws at the bark and then goes inside to lay eggs, and its larvae then start to eat inside the trunk and obstruct the nutritive path of the tree, which dies in about four weeks, "Arne Barkhausen, a forest ranger in Brandenburg, told AFP.
- "Unparalleled disaster" -
In other German regions, the situation is even more alarming, with hectares of forests destroyed in a few weeks in Bavaria, Saxony-Anhalt or Thuringia.
In Saxony, where the regional authorities denounce a "unique disaster", the German army has helped the overburdened foresters to evacuate the dead trees.
The task could quickly prove Herculean and the dramatic consequences if not stopped the spread of bark beetles, which have already devastated an area equivalent to 3,300 football fields, according to the government.
The forest covers a third of Germany, a country that had, at the time of the last forest census in 2012, about 90 billion trees and employs some 1.1 million people, more than in the industry automobile.
The government of Angela Merkel will try to provide answers Wednesday at a summit on the forest, a theme that has a dimension almost mythical in Germany, whose forests serve as a backdrop for many stories and legends and where the book from the German Peter Wohlleben, "The Secret Life of Trees", has become a bestseller.
But it is difficult to act against this proliferation, whose main cause is global warming.
"The starting point was a series of extreme weather events that started with the Friederike storm in January 2018. The drought of the summer of 2018 followed by a mild winter and prolonged drought this year weakened the weather. trees and caused the explosion of the bark beetle, "says Larissa Schulz-Trieglaff, spokesperson for the Forest Owners Association.
Adult bark beetles gave birth to one or even two generations of several tens of thousands of insects in one year. Due to warming, winters are less harsh and no longer kill hibernating beetles. These insects emerge more quickly from this period of sleep and it is now three, and sometimes even four generations, that emerge.
- End the monoculture -
Coleoptera decimate trees too weakened by drought to produce the sap that usually repels colonizing insects.
If a spruce, the favorite variety of bark beetles which represents nearly 30% of the trees planted in Germany, is "a victim of bark beetles, it can repel one or two generations, but in the third, it can no longer defend itself and dies", describes Hans-Werner Schröck, a member of the Rhineland-Palatinate Forest Office.
The situation is all the more alarming as the means of eradicating the insect are very limited.
"It's hard to cope, we can not use chemical processes, when the animal is already in the tree, it stays there", according to Derk Ehlert, in charge of the fauna and flora, the capital also confronted with the problem. "So we try to favor the natural enemies of bark beetles, including wasps that eat readily eggs and larvae".
But these are only "short-term solutions", warns Mr Biedermann. For him, the only way to overcome is to end the monoculture, when a single tree is planted on hundreds of hectares.
The Forest Owners Association also advocates for a diversification of German forests, with trees from other continents better adapted to warming, such as American red oak or Japanese larch.
It amounts to 2.3 billion euros the cleaning of forests and reforestation.
© 2019 AFP