Driving through the Harz region in central Germany feels like entering an eerie post-apocalyptic landscape. Row after row of gray, dry naked trees stretch into the sky like a sea of brittle needles. This decades-old forest has been reduced to a tree graveyard in just a couple of years. 

"Nowhere else in Central Europe can you experience the climate crisis like here in the Harz Mountains," said Roland Pietsch, head of the Harz National Park. 

Conifer forests across Germany are deteriorating under the combined pressures of droughts, storms and invasive pests, according to the latest government report on the state of the country's woodland. It's a similar story in Poland, the Czech Republic and Scandinavia. But some see this loss as a net positive for the climate in the long term. 

Spruce monocultures: A vulnerable legacy

To understand why forest loss might, in some cases, be a good thing, we need to rewind back to World War II. After Germany's defeat, the Allied forces ordered the country to pay reparations — partly in the form of timber. According to some estimates as much as 10% of all the country's forests were cut down to meet demand.

To make up for this, German foresters started planting large amounts of one specific tree: the spruce. That's because spruce trees grow fast and straight, which makes them ideal for timber production and construction. To this day, most of these forests are used to produce wood, with the forestry industry representing 1 to 2% of the country's GDP. The spruce is still one of the most common species.

But these monoculture forests are less hospitable to other plants and animals and are significantly less biodiverse than mixed ones. And as is the case with all monocultures, they're very susceptible to climate change-linked stresses like drought. 

The recent droughts in many parts of the world are especially hard on spruces because they are often planted at lower, drier elevations than they would grow naturally. Their root systems are also shallow, meaning they can't access water reservoirs deeper underground. 

Enter the bark beetle

While this is devastating for the spruces, one species loves these conditions: the bark beetle. The tiny insect is only a few millimeters long, but it's steadily been munching its way through much of Germany's and Europe's forests.

The beetle bores holes into trees, releasing pheromones to draw a mate inside. There, they reproduce and lay eggs.

"A pair can produce up to 100,000 descendants in a year. They spread like wildfire," said Fanny Hurtig, a forester in the central German Thuringian Forest, as she tears the bark off trees that had to be chopped down prematurely. The eastern state of Thuringia, three hours south of the Harz National Park, is one of the regions where the insect is spreading fastest. 

A healthy tree usually produces resin to seal up holes and protect itself from the beetles. But thirsty, weak trees cannot do this. The beetles eat away at the layers that transport nutrients and water around the spruces, which then die from thirst and malnutrition. 

Letting nature take its course

Back in the Harz, drought and infestation have killed about 90% of the spruce population. It's the hardest-hit region in Europe because of its large concentration of the tree species.

But Pietsch — and many others — don't see these swaths of dead trees as a disaster. 

"When I came here 2 1/2 years ago, much of this still looked dead. It takes two or three years, but then things start to come back to life. The forest that belongs here is coming," he said.

The Harz National Park decided to let nature take its course — and did not fight the bark beetle. And nature is doing its thing. Upon closer inspection, shrubs and young trees are springing up at the base of towering dead spruces. 

The first ones to take root were the pioneer tree species like the birch or willow, whose seeds are spread widely and quickly by the wind or birds. But the forest still needs a little help and formerly native species like beech are being reintroduced.

Dead spruce trees still play a role. They act as habitat for insects, provide shade and keep moisture locked in. Fungi help decompose the wood and add nutrients back into the soil. "When you see what kind of strength, how much life there is in it, it's beautiful," said Pietsch.

But the dead spruce trees also release CO2 while decaying, which means these forests store less CO2 overall compared to healthy ones. The hope is that the carbon-storage capacity of new trees growing in the Harz will compensate in the long-term.

How to future-proof the forestry industry

But that's just one part of the story. The national park is a protected area that is no longer used to produce timber. But just 3% of Germany's forests are protected.

Public or private foresters use the rest to produce timber, for example — an industry that is projected to grow as the demand for sustainable building materials increases. 

In Thuringia, foresters like Hurtig are forced to harvest huge numbers of trees before they reach maturity. As soon as the spruces are infested, they are cut down to halt the spread of the bark beetle.

Hurtig said felling so many trees prematurely does hurt. 

"My heart aches every day when I see this," she told DW. 

Still, foresters like Hurtig see it as an opportunity to create a more sustainable mixed forest with a variety of trees and to prevent future die-offs.

"It's also a chance to build up these areas in a more structured way and with completely different tree species," said Hurtig of what is happening in the Thuringian Forest, which is used commercially. 

The new species will have to survive with little water, ideally have deeper root systems to outlast more droughts and storms and cannot be too susceptible to pests. Native trees like beech, oak and sycamores as well as the North American Douglas fir are tipped as good candidates. 

But if climate change accelerates, trees from much warmer habitats, such as the Turkish fir or the Oriental beech, could be introduced too. 

Toward a more resilient forest

More German commercial forests and national parks are moving to create mixed forests that get closer to native ecosystems but are also resilient to pests and a warmer climate.

Bodies like Forest Europe, which aims to protect the continent's woodlands, are advising other countries with similar problems like France, the Czech Republic or Belgium to do the same. 

Seeing the full benefits of forest restructuring will take time, but "it's good from the perspective of the climate crisis and it's good for resiliency as well as biodiversity," said Pietsch. 

Correction: An earlier version of the map incorrectly referred to the area of the Harz National Park as Harz. This has now been corrected.

Edited by: Jennifer Collins