The forest continues to expand in France, but it is increasingly fragile, reports IGN

The equivalent of “130 football fields” of forest grows each year in France but tree mortality is twice as high as 10 years ago. Spruces, chestnuts and ash trees are most threatened.

The forest continues to expand in France, but it is more and more fragile, indicated Thursday October 10 on France Inter Manuel Fulchiron, deputy director, responsible for forests at the IGN, while the National Institute of Information geographical and forestry publishes its national inventory.

Since 1850 and “what we call the forest minimum”, recalls Manuel Fulchiron, the forest continues to expand in France. “In recent years, it has increased by another 90,000 hectares per year,” indicates the deputy director of the IGN in charge of forests, i.e. almost “130 additional forest football pitches each year”. France (55 million hectares) today has 17.5 million hectares of forest, the engineer calculates.

There are regions that are becoming more green than others. “It is especially in the West and the South-East that there is the greatest progression, mainly through colonization and reforestation of old agricultural land”observes Manuel Fulchiron. There are no longer any major reforestation campaigns, those known in the 1950s, 1960s or 1980s, recalls the deputy director of the IGN. In recent years, reforestation has been taking place “in small steps”.

But just because the forest continues to expand does not necessarily mean it is in good condition. IGN has been observing for several years “a silent storm that hits the forests”. Heat waves and drought always weaken the trees a little more. “They end up succumbing either from exhaustion, or from attacks of fungi, insects, various parasites which get the better of them”explains Manuel Fulchiron. A figure calculated by the IGN shows the widespread weakening of French trees: “15 million cubic meters of mortality is twice as much as ten years ago.”

In its national inventory published this Thursday, the IGN lists three tree species particularly affected by this increasing mortality. Spruce, a conifer threatened by an insect, the bark beetle. “Most of the trees are dying today.” explains Manuel Fulchiron. For several years, the chestnut tree has also been threatened, attacked by ink disease and canker. As for the ash tree, it is attacked by chalarosis. The latter three diseases are all caused by fungi native to Asia.

The IGN obviously advises against monoculture, which causes a single population that is less resistant to climatic or biological disturbances, which is not, moreover, “not suitable for forests”, underlines Manuel Fulchiron. The IGN national inventory, “this forest thermometer”, as the deputy director of the institute calls it, also allows “to orient, guide public policies”. For example, it is necessary to adapt to “new climate” and help with “migration of certain species which were further south and which must be installed further north to support renewal”. But, faced with the increasing weakening of French trees, the deputy director of the IGN concedes: “There is no magic recipe.”