why are chestnut trees threatened with disappearance in the forests of Île-de-France?


Video length: 2 min

Why are chestnut trees disappearing from the forests of Île de France?

Will there still be chestnuts in French forests in a few decades? In the forests of Île-de-France, more and more plots of chestnut trees are being razed. The cause is the incurable ink disease, which is thriving thanks to climate change. – (DAUPHIN / RADIO FRANCE)

In the Paris region, more and more chestnut plots are being razed. The cause: incurable ink disease, which is thriving due to climate change.

In the heart of the Fausses-Reposes forest, between the towns of Ville-d’Avray (Hauts-de-Seine) and Versailles (Yvelines), foresters cut down chestnut trees with chainsaws, Tuesday February 20. On the information board indicating the duration of the work, a disgruntled person wrote in black marker: “ONF MANURE, GARBAGE”. However, it is not with joy of heart that the National Forestry Office cuts down these trees. But because they are going to die, because of ink sickness.

“Ultimately, the chestnut tree in Île-de-France is almost doomed.”

Pierre-Emmanuel Savatte, NFB

at franceinfo

The pathogen, Phytophthora cinnamomi, called ink disease, has been present in the soil for more than two centuries“, explains Pierre-Emmanuel Savatte, territorial director of the ONF Île-de-France west, in front of a plot of diseased chestnut trees. “This pathogen is an oomycete, an organism that is somewhere between a fungus and an algae. The harsh winters limited its development. Climate change means that the pathogen is no longer limited in its development. And then, in spring, we have uncertain rainfall which means that the chestnut tree does not have sufficient water to grow. So, in the long term, the chestnut tree in Île-de-France is almost doomed”.

An ONF information panel announcing tree cutting in the Fausses Reposes forest in Ville d'Avray tagged (Hauts-de-Seine), February 20, 2024 (DAUPHIN / RADIO FRANCE)

There is currently no treatment to treat diseased chestnut trees. When the roots are affected, the crown of the tree first loses its leaves. Chestnuts are smaller when the tree is fruiting. Then little by little, the whole tree dies away.

In the Malmaison forest, a few kilometers from the Fausses Reposes forest, still in Hauts-de Seine, a plot of diseased chestnut trees will be razed at the beginning of March 2024.If we don’t cut them before they become dry, these chestnut trees will die near a path, in a forest very frequented by the public, worries Pierre-Emmanuel Savatte, who fears an accident. So we take them before they are definitely dead and dry. Otherwise, their destination is wood energy. This also allows you to make a small recipe“.

A plot artificially reforested in the Malmaison forest (Hauts-de-Seine) after a clear cutting of chestnut trees affected by ink disease, February 20, 2024 (Radio France/ Joachim Dauphin)

Indeed, dead, these chestnut trees would end up in a chimney. Collected in time, they can be sold by the ONF to make furniture or parquet flooring. These clear cuts, also called sanitary cuts when it comes to diseased trees, also make it possible to “prepare the forest of tomorrow“, recalls Mr. Savatte.

In this plot of Malmaison woods, razed three years ago, various species were planted in 2022. They were selected using software created by Inrae Climessences. This tool used by the ONF, accessible to all, allows you to choose species adapted to the soil and future climate. During these artificial reforestations, the shoots are planted in a row. They are protected from greedy deer by fences. Behind these protections, there are baby sessile oaks, small-leaved lime trees, wild service trees, corm trees and some conifers.

To see what the forest of tomorrow looks like, we will have to be patient: in 20 years, when the trees that have survived will be around ten meters tall.

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