Last year, spruce bark drills were a major problem for Swedish forest owners due to the hot weather. And despite a wetter and cooler summer this year, the new generation of fir bark drills also seems to be attacking the trees instead of going down into the ground to winter.
- The fir trees are dehydrated after last summer and therefore the attacks continue to increase. And that is an effect we will continue to see if we get warmer summers, says Patrik Karlsson, forest consultant at the Forest Board in Uppland.Attacks are also expected next year
In some places where the summer has been wetter, spruce bark drills have crept down to winter in the ground to resurface for new attacks next year. It is mainly in southern Sweden that the attacks are greatest, but even in Uppland there are now reported cases where new attacks have been discovered.
- The attacks are not as big here as in other places, but we can mainly see them between Uppsala and Enköping. If you look at fir trees along the road there you can see that they have brown cones, says Patrik Karlsson.Growing problems for forest owners
The phenomenon of spruce bark drills is not really new according to the Swedish Forest Agency. But you can see that the problem they pose will be exacerbated by climate change and warmer temperatures in Sweden.
- You knew this already in the 70s, but the scope is much larger now. Historically, you can also see that the Christmas tree does not feel so good around certain places along Lake Mälaren and then many choose to plant pine instead of avoiding problems, says Patrik Karlsson.
And the fir bark drill's actions hit hard for the forest owners' economy.
- If you find green-brown spruce flour under the spruce, you have to cut that part of the forest directly so that it does not spread, says Patrik Karlsson.