A new study predicts the likelihood of European spruce bark beetle damage, Ips typographus, at stand level in Finland, opening a path to proactive interventions for bark beetle management. Researchers at the University of Eastern Finland have identified stands where bark beetle damage is more likely to occur.

The study estimated the probability of individual forest stands to experience bark beetle damage. Using data from more than two million forest stands across approximately 11.4 million hectares in Finland, the researchers identified forest and landscape conditions where damage is more likely to occur.

Stand-level prediction across a national forest landscape

The researchers combined nationwide forest inventory data with disturbance and climate information collected between 2020 and 2022. The analysis included stand characteristics such as tree size as well as landscape features such as nearby disturbances.

The study shows that the landscape surrounding a forest stand strongly influences damage likelihood. Stands located close to previous bark beetle infestations or near clear-cut areas showed higher probabilities of damage. Stand characteristics, particularly larger tree diameters, also increased susceptibility to damage.

Short summer heat waves further increased the probability of bark beetle damage, highlighting how extreme warm periods can interact with forest structure and landscape conditions to influence the likelihood of infestation.

Supporting proactive forest management

Based on these results, the researchers produced a stand-level map identifying areas where bark beetle damage is more likely to occur. The map can help forest managers prioritise monitoring and target preventive actions before infestations start and spread.

“Our map reflects the situation in 2022. Forest managers and forest owners can use the map to check whether the likelihood of damage in their stand was high and, if yes, consider the need for more intensive monitoring and preventive measures,” says Alexander Pulgarín Díaz, PhD, of the University of Eastern Finland.

The study also highlights that disturbances such as clear-cuts, including those associated with salvage logging, may influence future infestation patterns in nearby stands.

By identifying the forest and landscape conditions that predispose stands to attack, the study provides tools for anticipating bark beetle outbreaks and improving forest health in boreal forests.

Stand-level likelihood maps are available at:
https://alexpulga.github.io/sprucebarkbeetle-likelihood-map-for-2022/