They endanger boreal forests as precious to the planet as the Amazon rainforest.

Bark beetles are ravaging conifers ever further north in Finland due to global warming.

These small, brown-colored insects prey on Picea abies, one of the most common tree species in Finland, and slowly destroy entire woods.

Pieces of their bark peel off, twigs fall from dead branches… Burrowing to lay their eggs, the beetles devour absolutely everything around conifers and end up killing them by preventing water and nutrients from the soil from reaching the branches. in height.

"These insects have been wreaking havoc across central and eastern Europe, especially from 2018," says Markus Melin, a scientist at the Institute of Natural Resources in Finland.

Trees already weakened by drought

The risk of seeing this epidemic spread is "much higher now" because of global warming, he argues.

“We have to accept it and adapt.

Things change very quickly.”

The threat is usually far greater in southern Finland, but the scorching summer of 2021 has seen bark beetles wreaking havoc "far north", in the Kainuu region.

“It's a well-known phenomenon: conifer beetles are one of the species that benefit the most from global warming to spread,” says Markus Melin.

These beetles choose trees already weakened by hot summers and lacking water, while increasingly warm winters and the absence of frozen ground make it difficult to protect trees from storms.

The acceleration of the "cycle of destruction"

The increasingly warm climate also accelerates the life cycle of bark beetles.

"Their mortality rate drops and they reproduce much faster," laments Markus Melin.

If they first choose the weakest trees, once they have become very numerous, the bark beetles attack the healthy trees.

If the forest guards do not react in time by removing the weakest trees, "all of a sudden the bark beetles, which have become very numerous, are able to attack the healthy trees", explains Markus Melin, " accelerating the cycle of destruction”.


“Something abnormal has been happening for more than a decade”, the mortality of trees worries


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