12/10/2024 – 6:35
Forests in the European country are impacted by the climate crisis and pest attacks. However, this situation offers the chance to make these ecosystems more diverse and resilient. The Harz mountain region, in central Germany, looks like a frightening post-apocalyptic landscape. Endless rows of dry, gray trees, like a sea of brittle needles. In just a few years, this ancient forest became a tree graveyard.
“Nowhere else in Central Europe is it possible to experience the climate crisis like here in the Harz mountains,” says Roland Pietsch, director of the Harz National Park.
Coniferous forests in Germany are impacted by drought, storms and invasive species, according to a German government report on the state of the country’s forests. But it’s not just German vegetation that faces this problem. The situation is similar in Poland, the Czech Republic and Scandinavia. Some, however, see this loss as a long-term positive for the climate.
To understand why the loss of forests can be, in some cases, a good thing, we need to go back to the Second World War. After Germany’s defeat, the Allies ordered the country to pay reparations. These were paid, in part, with wood. Estimates calculate that up to 10% of all forests in the country were cut down to meet demand.
To compensate for this devastation, German foresters began planting a specific species of tree: the fir. The choice was based on the qualities of this conifer: fast and straight growth, which makes the species ideal for wood production and construction.
The vulnerable legacy of monoculture
To this day, most of these forests are used for timber production, with the forestry industry accounting for 1 to 2% of German Gross Domestic Product (GDP). Fir is still one of the most common species.
But these monoculture forests are less hospitable to other plant and animal species, and they are considerably less biodiverse than mixed forests. And, as is the case with all monocultures, they are very vulnerable to stresses related to climate change, such as drought.
Recent droughts in many parts of the world are especially hard on spruce trees, which are often planted in lower, drier regions than their natural habitat. Their root systems are shallow, which means they cannot access underground water reservoirs.
While this is devastating for spruce trees, one species loves these conditions: the bark beetle. The small insect measuring just a few millimeters has devoured many forests in Germany and Europe.
The bark beetle makes holes in trees and releases pheromones to attract a mate inside. There, they reproduce and lay eggs. “A pair can generate up to 100,000 offspring per year. They spread like wildfire,” says Fanny Hurtig, a forester in the Thuringian Forest in central Germany.
The state of Thuringia, which is three hours south of the Harz National Park, is one of the regions where the insect spreads most quickly.
A healthy tree will usually produce resin to close holes and protect itself from beetles. But those that are weak and dry cannot defend themselves. The beetles eat the layers that transport nutrients and water in spruce trees, which eventually die.
Let nature take its course
In the Harz, drought and infestation killed around 90% of the spruce trees. Due to the large concentration of tree species, this is the most affected region in Europe.
But the director of the Harz National Park, like many others, does not see these swaths of dead trees as a disaster. “When I got here two and a half years ago, a lot of it still felt dead. It took two or three years for life to be reborn. The forest that belongs to this place is coming back”, says Pietsch.
The Harz National Park decided to let nature take its course, and did not combat the bark beetle. And nature is doing its job. Closer inspection shows that shrubs and young trees are sprouting in the region where there are huge dead firs.
The first to take root were pioneer tree species such as birch or willow, whose seeds are spread widely by wind and birds. But the forest still needs a little help. Thus, native species, such as beech, are being reintroduced.
Dead firs still have a function. They serve as habitat for insects, provide shade and keep moisture trapped. Fungi help decompose wood and add nutrients to the soil.
“It’s beautiful to see the amount of strength and life present there,” says Pietsch.
However, dead fir trees also release CO2 as they decompose, meaning these forests store less carbon than healthy ones. The storage capacity of the new trees growing in the Harz is expected to compensate for this in the long term.
Wood production
But this is only part of the story. The national park is a protected area that was no longer used for timber production. However, only 3% of German forests are protected areas. All others are focused on wood production – an industry that is expected to grow with an increase in demand for sustainable construction materials.
In Thuringia, foresters like Hurtig are forced to cut down many trees before they reach maturity. Once spruce trees are infested, the tree is cut down to prevent the spread of the bark beetle. “My heart hurts every day when I see this,” Hurtig says.
The forester, however, sees the situation as an opportunity to create a more sustainable mixed forest. “It’s a chance to plant completely different tree species in these areas,” highlights Hurtig.
The new species need to survive with little water, ideally they should have deeper root systems to withstand droughts and storms, as well as being more resistant to pests. Native trees such as beech, oak and maple, as well as Douglas fir, from North America, are considered good candidates. But if climate change accelerates, species from warmer habitats, such as Turkish spruce or eastern beech, are good options.
More resilient forests
More of Germany’s national parks and private forests are moving to create mixed forests that more closely resemble native ecosystems and are more resistant to pests and a warmer climate.
Bodies such as the Ministerial Conference for the Protection of Forests in Europe are advising other countries with similar problems, such as France, the Czech Republic or Belgium, to do the same as Germany.
It will take time to see the benefits of forest restructuring, but “it is good from the perspective of the climate crisis and it is good for resilience, as well as for biodiversity”, adds Pietsh.
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