The relatively cold early summer has slowed down the spruce bark beetle’s activity, but there is no end in sight for the forest damage – drones are used to detect damage to trees faster than before

The spruce bark beetle population has strengthened, and the areas of damage have spread further north, and this trend seems to be continuing. The spread has been particularly affected by the warming climate, the dry summer seasons and wind damage.

In its research projects, the National Land Survey’s Finnish Geospatial Research Institute (FGI) has developed a method based on photography carried out by drones and artificial intelligence analysis that can detect the impacts of spruce bark beetles and the deterioration of trees much better than the human eye.

Research Professor Eija Honkavaara finds that the method has potential for preventing spruce bark beetle damage.

“Our research has two main objectives. First, our aim is to monitor the progress of the spruce bark beetle damage. This allows us to see the direction in which the damage is advancing and to target the actions at the right areas. Second, we are developing methods to find the individual trees contaminated by the spruce bark beetle at an early stage. This would allow precise actions to be taken to control the damage.”

The artificial intelligence method looks for individual spruce trees in the photographs taken by drones and classifies them as healthy, deteriorated and dead.

“From the hyperspectral images collected with drones, it was already possible to detect the fresh impacts of spruce bark beetles within 3 to 5 weeks, while the tree tops were still green. The result is promising, as it provides time to react before a new generation can develop into adults and swarm towards new target trees. In addition, we are developing new mapping drones that fly inside the forest and can immediately find the impacts,” Honkavaara says.

Damage is also visible in the Helsinki region

The variation in the numbers of spruce bark beetles, the change in the health of trees and the progression of forest damage are also studied with pheromone traps for the beetles and by monitoring symptoms in trees in test areas. The data is used to train the artificial intelligence.

One of the test areas is in Paloheinä, in Helsinki. The research team has been monitoring the situation in the area since 2020.

“In the starting situation, there were 14 dead spruce trees per hectare in the research area. Between 2021 and 2024, there were 6 to 8 more of them per hectare per year. So, during the monitoring period, the spruce bark beetle killed about 40 spruce trees per hectare,” says Research Scientist Emma Turkulainen.

This year, the cold early summer has slowed down the reproduction of spruce bark beetles. For example, only one generation of beetles is expected in Paloheinä this summer. However, it is likely that forest damage caused by the beetles will continue to spread in the coming summers.

“Our research enables forest health monitoring that can be scaled to cover large areas and has low emissions. Drone-based technologies can also be combined with satellite remote sensing. With the aid of these methods, it will be possible to study the impact of the environment and conditions on the health of trees more extensively,” Eija Honkavaara says.