Forced to cut down the trees - to save the forest

- We must cut down the trees to preserve as many healthy firs as possible. We are trying to stop the spruce bark drill from continuing to spread, ”says Thomas Weissenberg, Linköping Municipality's forest manager.

Since the dry long summer 2018, it is much more spruce bark drill than before. They threaten 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.

See the ravages in Rydsskogen with Thomas Weissenberg and SVT's reporter among harvesters and boreholes, in the clip above.

Last year, Linköping Municipality needed to cut around 2,500 cubic meters of spruce forest and right now about 200 firs are being felled in Rydskogen. Trees around 60, 70 years old. Along the walking paths in the Rydsskogen it is very well seen.

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

It is mainly the forests in southwestern Östergötland that the Swedish Forest Agency points out - the parts of the county where the older spruce forests are mainly located.

The Swedish Forest Agency estimates that a total of 23 percent of Östergötland's forest land area has a medium or high risk of attack by spruce bark. But says at the same time that it is a much smaller part that really gets attacked.

- Yes, the risk of attacks is greater along the coast, that is along the eastern edge of the county, says Mattias Sparf, the Swedish Forest Agency's forestry consultant and damage coordinator for Östergötland.

- This is because the firs there have a higher stress level due to 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.

More than 1 million cubic meters of spruce forest were damaged in the county last year, according to the latest estimate from the Swedish Forest Agency. The value was SEK 430 million, ie almost half a billion.

- We do not know how much damage we received so far this year. And how big the damage will be depends on the weather, 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.

- We are currently experiencing a breaking point. So far, double heating has occurred two, three times in 10 years. But in 30, 40 years it will instead be only two, three seasons in 10 years, when it is not double heating, says Mattias Sparf.

The Forest Board's map shows, among other things, that there is a greater proportion of forests in high risk classes in the counties Blekinge, Västmanland and Jönköping, but the situation is also serious for other counties in southern Sweden. What contributes to a high risk rating is, among other things, a lot of spruce, proximity to hygiene and previous attacks, as well as dry land.

Last year, the spruce bark drill caused damage to spruce forests equivalent to 7 million cubic meters of forest worth several billion SEK, especially in southern and central parts of Sweden.