Germany’s dying forests are losing their ability to absorb CO2. Can a new way of planting save them? | Germany

EEven the intense green of late spring cannot hide the dead trees of the Harz Mountains. Standing tall on the gentle peaks of northern Germany, thousands of skeletal trunks mark the remains of a once great spruce forest.

Since 2018, the region has been ravaged by an epidemic of tree-killing bark beetles, made possible by successive droughts and heatwaves. He transformed a landscape known for its verdant beauty into one dominated by a sickly gray.

This loss sparked awareness of modern forestry methods pioneered by Germany, which often rely on swaths of monoculture plantations. The ferocity of the beetle epidemic means there is no going back to the old way of doing things: replacing dead spruce trees with saplings of the same species would likely guarantee another catastrophe.

Instead, foresters experimented with a different approach: pockets of beech, fir and sycamore were planted around the surviving spruce trees to ensure that the returning forest was richer in biodiversity. They hope planting a mix of species will make the landscape more resilient.

“There were times when we had no confidence in what we were doing,” says Mathias Aßmann, spokesman for the regional forestry company responsible for this part of the massif, pointing out the scars in the landscape from a hilltop.

“You spend the whole day cutting down infected trees. The next day too, and the day after that. For months. All year round: cutting, cutting, cutting. Many colleagues have symptoms of burnout,” he says.

The rapid loss of trees has sparked renewed attention to how nature can be used to meet climate commitments in a warming world.

VDisaster diebacks, like those seen in the Harz Mountains, are becoming more common in Europe as the climate warms, leading to extreme weather and droughts. At the height of the bark beetle epidemic between 2018 and 2021, Germany lost half a million hectares (more than 1.2 million acres) of forest, or almost 5% of the country’s total.

The Czech Republic has lost even more in relative terms and Norway, Sweden, France and Finland are seeing changes as Europe’s ecosystems are strained by increasing heat and drought. New research from the UK indicates that ancient forests are finding it increasingly difficult to regenerate. Greek foresters report a considerable decline in the country’s fir trees and peat bogs across Europe are drying up.

The consequences are starting to be felt in official statistics. In July, scientists published a significant downward revision to the amount of carbon removed from EU land, due to the weakening of the forest carbon sink. Since 2010, the amount absorbed by land has decreased by a third and continues to decrease.

Figures published in 2024 in Germany show a significant increase in emissions between 2017 and 2022 due to the bark beetle epidemic and drought, like other Member States. Experts say the speed at which the amount of carbon absorbed by European forests is falling was unexpected and is already putting climate targets out of reach.

“The EU and Germany can set their policy targets, but… what we have seen since 2018 is that forests are heavily affected by drought. This is significant dieback. We have huge carbon stocks that are dying and no longer contributing to a carbon sink,” says Professor Matthias Dieter, director of the Thünen Forestry Institute, explaining that Germany is now almost certain to miss its carbon sequestration target for land.

“You can’t force the forest to grow – we can’t control what its contribution to our climate goals should be,” he says.

The debate over whether it makes sense to include the role of land and nature in national climate goals is intensifying among experts. Supporters say it requires governments to think carefully about their natural resources and push them to harness nature to help absorb greenhouse gases.

Forests, oceans and other natural carbon sinks already absorb about half of human emissions – and any increase could contribute. But many argue it should be separated because it allows governments to assume that nature can replace decarbonization.

“What’s happening is that countries are using their carbon sink – or their assumptions about their carbon sink – to compensate for slowing the phase-out of black carbon sources like oil, coils and gas. This is very dangerous because it means that countries can use their carbon sink from forests to claim that they are carbon neutral without completely phasing out fossil fuels,” says Johan Rockström, director of the Potsdam Institute for Climate Impact Research.

Countries like Finland have already become examples of the risks of this approach. The Nordic country aims to become carbon neutral in just ten years, in 2035, by using huge forests and peatlands that cover 70% of the country to extract carbon from the atmosphere. But since 2010, the amount of carbon absorbed by these countries has declined significantly and their forests and peatlands have in recent years become a small net contributor to global warming.

OhEn route to a hearty lunch of curry sausages and fries, Aßmann and fellow forester Ralf Krüger stop the car further down the valley to show off their vision of the Harz Mountains. We walk through a mass of aerial greenery, where a mix of species grow. Huge oaks, maples and beeches grow into the canopy, while young Douglas fir and spruce saplings cover the ground below. Dappled sunlight on the forest floor contrasts sharply with dark areas of spruce monocultures that have survived the bark beetle.

“We use this to show people our idea for the future,” says Krüger.

Here, instead of cutting down dead trees, the national forestry company focuses on using biodiversity to improve the resilience of rebuilding forests by planting a mix of species. Over time, it is hoped the species will provide a diverse landscape that it can selectively harvest while avoiding a calamity similar to recent bark beetle outbreaks.

International research has shown that biodiversity can help protect forests against drought: a 2018 study in Nature found that tree diversity provided the best protection against drought mortality, and research published in PNAS last year found that species richness protected tree growth during prolonged drought seasons. Monocultures are far more vulnerable – not only to drought, but also to disease outbreaks, bark beetles and wildfires, which eat away at all the planet’s carbon sinks.

The Harz mountain range has already withstood major challenges. It has suffered large-scale forest loss from mining since the 16th century. In the 1980s, acid rain from coal emissions in the East fell on trees, killing some trees here. Before that, it was World War II, during which large areas were razed to pay for British reparations in the aftermath. But Aßmann says a new approach will be needed in an era of intense global warming.

“Even if there are pests like bark beetles on the spruce, it doesn’t matter because there are young trees underneath. They can grow and the forest as a whole will not disappear because there is only a spruce next to a Douglas fir, next to the beech, etc.,” he says.

According to Aßmann, these healthier forests can also offer hope to those disturbed by the loss of trees.

“Many people have worked in these forests for 40 years and in just three years all their work is gone: they cut it down and put it in a truck. It’s very hard for them. So this place is good for their soul. It’s a good goal for them to work for,” he says.

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