"It's a disaster": Is the forest lost after a fire?

Also this year there are terrible pictures of forest fires.

"It's a disaster": Is the forest lost after a fire?

Also this year there are terrible pictures of forest fires. In Germany, the fire brigade has to fight the fires for weeks. Once the fire is out, the greatest danger is averted. But what will become of the forest afterwards? Can he recover?

"The trees and many other creatures that made up the forest are lost due to the fire," explains Jens Schröder, professor at the University for Sustainable Development in Eberswalde in an interview with ntv.de. But "Forest fire is not just a forest fire." It is therefore difficult to name an exact period of time when the forest will have fully recovered.

There are more harmless fires, such as a ground fire. This spares the treetops and the fire brigade can extinguish it relatively quickly. "A healthy forest can withstand this without the majority of the trees dying," says Schröder. More fatal for the forest are the larger fires, in which the trunk of the tree is so severely destroyed that the tree slowly dies as a result of the fire. The forest is also much more susceptible to new fires if it has already burned before and has dried out as a result.

Normally, after a forest fire, the remains of the trees, the so-called deadwood, are removed to make room for young trees. After a forest fire in 2018, researchers in the Brandenburg municipality of "Treuenbrietzen" wanted to find out whether the dead wood is not even useful for the plants growing underneath and should therefore be left lying around. Tragically, the area burned down again before the investigation was completed.

How quickly a forest becomes green again after a fire depends primarily on the size and severity of the fire. In Brandenburg, for example, there are several small forest fires every year that can be quickly extinguished. The former fire area is already green again after six months to three quarters of a year. And within a few years, the free space grows from the outside inwards again.

The first five to ten years are crucial for young trees. In an open area, these are little or not protected. They are then exposed to wind, frost, precipitation and solar radiation. That is why it can happen that young trees die again after two to three dry years. However, it will take several decades for the forest to regain the same density as before the fire. In 2018, many forests that were 60 to 70 years old burned down in Brandenburg. It takes exactly the same amount of time, ie 60 to 70 years, for these forests to fully recover.

Man cannot simply replant the forest, he can only support nature in its rehabilitation. Reforesting directly into the burned forest floor would hardly be successful. The forest floor could not supply the newly planted trees with nutrients. In addition, this process would be very expensive. So-called pioneer plants, such as the "silver birch", can really help. These are trees that make little demands on their surroundings and grow particularly quickly in the first ten to fifteen years. They offer protection to the slower growing trees in several ways.

In 2021, 42 hectares burned in Brandenburg in 168 fires. Climate change will continue to increase the numbers in the coming years and the extreme drought means that fires can spread faster. "In our region, i.e. in Central Europe, forest fires are not natural," says Schröder. Over 90 percent of forest fires are man-made. Only four percent of fires have natural causes, such as a lightning strike. "The forests come here with us completely without forest fires and are not prepared for it. It's really a disaster," he continues. "An ecosystem always disappears," says the scientist.

If there has been a fire, some individual animal or tree species can also benefit because there is more free space after a fire. They can grow better and claim a new habitat for themselves. In addition, after a fire there is an opportunity to redesign the forest. In Brandenburg, the forests consist mainly of conifers, which burn particularly easily. If these forests are destroyed by fire, this is a chance to make the forest that grows back more fireproof. Mixed forests, i.e. forests that consist of many different types of trees, are considered to be more fire-resistant. "You have to be patient and also accept that the forest does not deliver the product 'wood' right from the start," says Schröder about the expectations that people all too often have of the forest.

By the way: Conifers such as pine, spruce and silver fir contain many essential oils and therefore catch fire particularly quickly. But there are tree species, such as the "red oak", which are planted preventively, i.e. to protect against forest fires. However, it is an American tree species, which is why it is not allowed to be planted in nature reserves in this country.

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