Researchers have been called for help in the Landes to save the pine forests that line the dunes, as the youngest trees can no longer grow. At the end of a real investigation, researchers from the ONF, INRAE ​​and the University of Bordeaux managed to isolate a culprit and his accomplice.

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We must save the pines of the Landes. Researchers have been called upon to help save the pine forests that line the dunes in this region of southwestern France. For the past twenty years, the National Forestry Office (ONF) has noticed that more and more young pines can no longer grow. Often, these do not even spend the summer. A phenomenon that endangers the regeneration of 100,000 hectares of dune forest.

Researchers from the National Research Institute for Agriculture, Food and the Environment (INRAE), the National Forest Office (ONF) and the University of Bordeaux have therefore embarked on an investigation to identify those responsible.

"A culprit, and an accomplice"

For three years, they surveyed the dune forests around Biscarrosse. The researchers, including Laurent Augusto from INRAE, wanted to understand why many young pines died in this sector, dried out, to the point of sometimes disappearing. "It was built like a police investigation," explains Laurent Augusto. "To explain these disappearances, we had a lot of suspects. It could be linked to the weather, or to new emerging diseases."

The stake is considerable, because if the forest is used to stabilize the dune, it is also used for the wood and paper industry, second source of employment in Aquitaine. After three years of sampling and autopsies, the noose finally tightened.

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"We found a culprit, and an accomplice. The culprit was climate change: in the sector the summers are drier, which is enough to grill the young seedlings. As for the accomplice, it is a sector where there has more animals that come to eat very young trees, deer, deer ... "

In order to limit the presence of these "accomplices" as much as possible, the hunting quotas have been increased. In terms of heat, the NFB has changed the way it does business. Less clear cutting before replanting seeds, letting large trees serve as umbrellas for young shoots… A new policy that works: in the test areas, young pines are six times more likely to survive.