What prevents the pines lining the Landes beaches from growing? It is to answer this question that researchers from the National Research Institute for Agriculture, Food and the Environment (Inrae), the National Forest Office (ONF), and the university from Bordeaux, embarked on a real investigation, "scientific police" way, to identify the culprits. Especially since the stakes are high: it is the regeneration of more than 100,000 hectares of dune forest that is threatened. For three years, they therefore surveyed the forests around Biscarrosse to understand why, in this sector, many young people died dry or disappeared.
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"A culprit and an accomplice"
"There was nothing suspicious, and it could be linked to the weather or to new emerging diseases," recalls the microphone of Europe 1 Laurent Augusto, from INRAE. But after thousands of samples, the noose tightened. "What we found was that there was a culprit and an accomplice," he explains. "The culprit is probably climate change in the sector: the summers are a little drier and that is enough to grill the young seedlings. As for the accomplice, it is the increase in animals who come to eat the very young trees, especially deer. "
A parasol effect
So to limit the nuisance of the latter, hunting quotas have been increased. And to counter the effects of the heat, the NFB changed its rifle by stopping the clearing before planting seeds. The large trees thus become parasols in the shade of which the young shoots can flourish. And it is a success, since they are now six times more numerous in these areas.