The pine trees that are currently turning to ashes one by one in the western French Gironde were not there by accident. Together they form the Forêt de Landes: the largest planted forest in Europe, covering some 1 million hectares. of which 20,000 hectares gone up in smoke since the wildfires started a good week ago.
The forest is an economic gold mine: the wood of the fast-growing pine trees is used for the production of paper, specially certified construction wood and biomass. Such a huge forest is also good for the capture of CO2, you could say. But the problem is that there are only pine trees in the forest.
“There is a monoculture: there is only one type of trees and they are all neatly arranged in a row,” says Jean-Baptiste Filippi by phone, who is researching forest fire prevention for the University of Corsica. This is useful for forestry, but “monoculture also provokes extreme events,” says Filippi. Like the storms from 2009, with trees that fell and took countless others with them, like falling dominoes. And like burning.
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“Fire can spread more easily over great distances in homogeneous forests,” Eric Rigolot, director of the Research Unit for Ecology in Mediterranean Forests, also said on the phone. To fight fires, he says, “it is better to have more mixed forests, with different tree species, little undergrowth and open spaces.” That way the fire can’t jump from tree to tree so easily. An additional advantage is that such a forest promotes biodiversity.
What has made the situation in the Gironde even worse is the type of tree itself. “Pine trees allow sunlight to pass through, creating undergrowth on the ground.” This undergrowth ensures that fire can also be transmitted vertically: if the grasses and bushes under a tree catch fire, the heat rises and the tree also catches fire. In addition, conifers like pines are highly flammable and combustible – more than most deciduous trees. And to top it all off, many of the trees in the Forêt de Landes are relatively young, which means they have lower branches and therefore themselves contribute to the upward spread of the fire. Rigolot: “It’s an explosive cocktail.”
heat waves
Yet not all blame can be placed on the pine trees or their planters. “Under these meteorological conditions, absolutely everything burns,” emphasizes Rigolot. He points to the heat wave that recently took place in the Gironde (and the rest of France) and further dried out the already very dry area. This one canicule combined with a strong and direction-changing wind caused the fire to spread rapidly.
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According to Rigolot, it is therefore not necessarily necessary to replace all monoculture in forestry with super-diverse forests as soon as possible. More important is prevention: encourage people who live in and around the forests to remove the easily flammable undergrowth – which they do, by the way. legally required are – and set up systems to protect people and infrastructure from the fires, which are sure to return.
A better climate policy is equally important. “Basically it is a climate issue. The most important thing is that society realizes this and takes action,” says Rigolot.
Filipi also hopes that the forest fires will help to open our eyes to the catastrophic consequences of climate change. “Perhaps this fire can help as a kind of publicity campaign, to emphasize that we really need to change our way of life now.”