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German Federal States — News — Braunschweig — Future — Freiburg — Germany — science — pest — Forestry — forest — Julius Kühn-Institut — Ecology — Rank — Quedlinburg — Fichte — Climate — Bourgain Beetle

Fir trees are nowhere safe from beetles

For some specialists, 650 meters was the limit: In mountain regions above this height, the spruce tree was still expected to have a future. But it seems that those times are over.

,   and  Lauren Adams
3 min read
The inside of this pine bark shows signs of beetle larvae.
The inside of this pine bark shows signs of beetle larvae.

pests in the forest - Fir trees are nowhere safe from beetles

Long ago, the height locations of German Mittelgebirge were considered safe sites for Fir trees - but even there, the Pine Bark Beetle attacks the needle trees. "Nothing is safe anymore", said Henrik Hartmann, head of the Forest Protection Institute at the Julius Kühn-Institut in Quedlinburg. "The Pine Bark Beetle now also infests the stands in the height locations."

In the Mittelgebirge, lower temperatures prevail than in the lowlands. "We used to think: The Pine Bark Beetle doesn't like it in the height locations above 650 meters", said Hartmann. "There, a beetle could occur occasionally, but massive infestations we didn't see there before. Drought and storms, which often caused stress to the trees, created easy attack points."

Few large Fir trees left in the Harz

Michael Rudolph, press spokesperson for the Niedersächsische Landesforste, has observed this development for several years. "From 2018 to 2022, we had strong to massive infestation in the Harz, even in the highest mountain ranges." Now, there are fewer Pine Bark Beetles - simply because there are fewer strong, mature trees. "This year looks good, there was also a lot of rain and rather cool weather, which helps the trees."

Pine Bark Beetles specialize in Firs. They bore into the trees and lay their eggs under the bark. After hatching, the larvae feed on the sapwood, in which the tree transports water and nutrients. If the bark is destroyed, the tree dies. Trees that are weakened by drought are particularly susceptible to infestation.

Even discovered at 1500 meters

Markus Kautz from the Forstliche Versuchs- und Forschungsanstalt Baden-Württemberg explains that the Black Forest is also affected: "The temperatures are sufficient in height locations from 1000 to 1500 meters for the Pine Bark Beetle to emerge, infest Firs, and reproduce." There, one can now observe one to two generations per year. In lower altitudes, three or even four generations are often detected.

The Pine Bark Beetle infestation is also shifting "slowly upwards" in Bavaria, says Tobias Frühbrodt from the Forest Protection Department. "In the Bavarian Forest, we currently have a lot of infestation, definitely up to 1000 meters. In the alpine forest in Southern Bavaria, there is still no massive infestation, as we have higher precipitation at the Alpine fringe." However, in Austria, there are Pine Bark Beetles even clearly above 1000 meters, up to 1600 meters high.

Should we then, aside from perhaps a few mountain forests in high altitudes, get used to a future without Firs? "We don't want and won't eradicate them", says Rudolph from the Niedersächsische Landesforste. "But they will no longer stand in monoculture outside their natural habitat."

Johannes Schmitt, managing director at the German Forest Industry Council, says the same: "We no longer consider Firs as a monoculture to be secure. Only in small percentages in a mixed stand does it have a future." In such a forest at high altitudes, for example, White Spruce, Beech, European Ash, Oak, European Beech, Douglas Fir, Larch, and also Fir could stand - depending on the location.

A problem is, that forestry takes a long time. "A tree grows for several decades," explains Schmitt. Therefore, Rudolph adds, let's first leave every spruce that's doing well. "Every living spruce tree still casts a shadow, we are grateful for every old tree that lasts a few more years."

LWF: Pine Beetle Year 2023 Nationalpark Bayerischer Wald: Printer's Situation

  1. The Pine Bark Beetle infestations have even been detected at elevations as high as 1500 meters in the Black Forest, according to Markus Kautz from the Forstliche Versuchs- und Forschungsanstalt Baden-Württemberg.
  2. In the future, Firs may no longer be considered a secure monoculture outside their natural habitat, as stated by Johannes Schmitt, managing director at the German Forest Industry Council.
  3. Henrik Hartmann, head of the Forest Protection Institute at the Julius Kühn-Institut in Quedlinburg, expressed concern about the Pine Bark Beetle infestations in the height locations of the German Mittelgebirge.
  4. The Bourgain Beetle, like the Pine Bark Beetle, poses a threat to forest ecosystems and is under study at the Julius Kühn-Institut in Braunschweig, part of Germany.
  5. The ecology of forest stands in Germany is being impacted by changing climate conditions, making trees more susceptible to pests such as the Pine Bark Beetle.
  6. The city of Fichte in Quedlinburg, Germany, is known for its rich history and close proximity to forests, which are currently under threat from the Pine Bark Beetle.
  7. The German Institute of Forest Ecology and Forest Management in Freiburg, Germany, is conducting research on forest management strategies to mitigate the impacts of the Pine Bark Beetle and other forest pests.

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