Forced to cut down the trees - to save the forest

"We must cut down the trees to preserve as many healthy firs as possible and try to stop the spread of the fir bark," says Thomas Weissenberg, Linköping Municipality's forest manager.

Since the dry long summer of 2018, it has been much more spruce bark drill than earlier, threatening old spruce forests all over Europe.

- That summer they had a hard time twice and we have attacks in many different places in the municipality.

Last year, the Municipality of Linköping needed to cut around 2,500 cubic meters of spruce forest and now about 200 firs are being felled in Rydskogen. Trees that are 60-70 years old. Along the footpaths it can be seen.

- Here we will plant both pine and noble leaves instead, mostly oak, says Thomas Weissenberg.

It is mainly the older spruce forests in southwestern Östergötland that the Forest Agency points out. A total of 23 per cent of Östergötland's woodland area has a medium or high risk of attack by spruce bark. But at the same time, a significantly smaller portion is being attacked.

"Yes, the risk of attacks is greater along the coast," says Mattias Sparf, who is the Swedish Forest Agency's forestry consultant and damage coordinator for Östergötland.

- This is because the firs there have a higher stress level after the early summer drought. If the trees are just healthy, their resistance to the spruce bark drills is considerably higher, even if they are old.

Just over 1 million cubic meters of spruce forest were damaged in the county last year to a value of SEK 430 million, according to the Swedish Forest Agency. 

- How much damage we received this year is unclear and depends on the weather ahead, says Mattias Sparf.

Dry and warm weather favor the bark drillers whose swarms usually get started properly at the end of May - June. If the summer is long and hot, the new generation can also swarm the same summer they hatched. Climate change causes this phenomenon to occur more frequently.

The Forest Board's map shows that a greater proportion of the forests in high risk classes are located in Blekinge, Västmanland and Jönköping. Sweden. Last year, the fir bark drill caused damage to spruce forest equivalent to 7 million cubic meters of forest worth several billion SEK.