Photo: Tuomas Kinnunen, NLS FGI
Driven by climate change-induced drought and heat waves, bark beetle populations multiply, spreading northward and affecting larger areas of Norway spruce stands in Finland. In Koli, researchers used an unmanned, low-emission airship to monitor and prevent bark beetle damage.
In Koli National Park, Finland, an innovative unmanned, low CO2 emission airship, manufactured by Kelluu Ltd., has been used to monitor areas disturbed by bark beetles, collecting remotely sensed data for identifying changes in tree crowns, including alterations in needle colour. These data are crucial for assessing forest health, particularly in investigating the symptoms of Ips typographus infestations that severely impact Norway spruce stands in Finland.
Conducted in collaboration between the University of Eastern Finland (UEF) and the Finnish Geospatial Research Institute (FGI) of the National Land Survey of Finland (NLS), the research involves coordinated field and aerial campaigns led by Prof. Eija Honkavaara (FGI NLS) and Prof. Päivi Lyytikäinen-Saarenmaa (UEF). Prof. Päivi Lyytikäinen-Saarenmaa outlines the objectives, emphasizing the development of a method for efficiently identifying trees colonized by bark beetles through remotely sensed data analysis. The goal extends to estimating potential declines in tree physiological condition. Another objective is the design and validation of models addressing damage risk and propagation dynamics specific to Finland’s environmental conditions. To achieve this, a systematic weekly field monitoring regime has been established to observe the symptoms in bark beetle-infested spruce trees and discern any ensuing changes.
Throughout the summer of 2023, a hydrogen-powered unmanned airship, belonging to Kelluu Ltd., collected accurate multispectral and RGB images of beetle-disturbed stands in Koli NP. This innovative technology represents a significant advancement in sustainable aerial monitoring, as the low-emission airship can fly for 12 hours daily with no carbon dioxide emissions. While the researchers have previously employed drones and AI for gathering forest data, the use of airships in Koli marks the introduction of the latest technological advancement in this field. Prof. Eija Honkavaara highlights the airship’s agility and speed in detecting bark beetle damage, underscoring its cost-effectiveness compared to traditional methods such as airplanes or helicopters.
In Koli NP, the airship monitored 28 circular sample plots, each with a 10m radius, established and georeferenced in 2022-2023. Simultaneously, ground reference data is being collected to validate and extend the remotely sensed data. The on-site fieldwork design incorporates the recording of tree morphological parameters (dbh, height), distance, and direction from the plot centres. Visual assessment of tree-level symptoms occurs every second week to track the symptom development. For analysing tree growth dynamics, 30 dendrometers were installed in beetle-affected (n=22) and control (n=6) plots located at different altitudes. Weekly data on bark beetle catches are recorded using 12 pheromone traps (4 x 3 traps) on UPM Kymmene’s clear-cutting area, positioned at the opposite side of Koli National Park, to monitor bark beetle swarming and population density dynamics. The traps, equipped with Model Ecotrap, dispenser type IT-Ecolure Mega (Fytofarm Ltd.), aim to measure the physiological condition of spruce host trees. In May 2023, 30 dendrometers were installed on six sampling plots.
The Koli NP, renowned for its rolling hills, old-growth forests, lush herb-rich woodlands, colourful meadows, and rare butterflies, attracts visitors and tourists from across Finland and abroad. Both natural ecosystems and traditionally managed landscapes coexist in Koli, providing habitat for 4078 different species, half of which are insects. Forest restoration efforts include retaining in-situ decaying wood, previously removed from monocultural commercial stands.
The Koli area faced severe snow damage in 2018 and winter 2023, along with very dry and warm summer periods preceding the outbreaks of I. typographus and other spruce bark beetles (Pityogenes chalcographus, Polygraphus poligraphus, etc.), Tetropium spp. Multiple symptoms of bark beetle infestation were detected on Norway spruce stems and crowns, including entrance/exit holes, boring dust, resin flow, bark damage, defoliation, and needle discoloration.
Given the outstanding ecological, aesthetic, social, and economic value of the Koli conservation zone, mitigating the consequences and preventing the spread of bark beetle damage in the National Park and adjacent areas is of paramount importance for natural ecosystem functioning and future generations. The integration of artificial intelligence, unmanned airships, and terrestrial data not only represents a significant technological leap but also underscores a commitment to sustainable and impactful solutions in the realm of forestry research and management.
More information
Eija Honkavaara, Research Professor, FGI, +358 29 531 4716
Päivi Lyytikäinen-Saarenmaa, Senior Scientist, University of Eastern Finland, Department of Forest Sciences, +358 40 8254465
The study is part of the RESDINET project funded by Horizon Europe. The project enhances networking activities between research institutions in widening countries (Institute of Forest Ecology, Slovak Academy of Sciences, IFE SAS) and top-class counterparts at the EU level (Finnish Geospatial Research Institute, the University of Eastern Finland, and the Swedish University of Agricultural Sciences). An initial network will be established and a new shared research project will be developed in the project, focusing on the application of new remote sensing technologies (RST) in the forest disturbance ecology. The project builds on networking for excellence through the transfer of knowledge and the exchange of best practices between the involved institutions.
Research groups are part of the Academy of Finland flagship UNITE that researches and develops the Forest-Human-Machine Interplay by for world’s leading research groups in forest sciences, spatial data and sensor development, as well as gamification. The UNITE is a flagship consortium of School of Forest Sciences of University of Eastern Finland, Natural Resources Institute Finland, Finnish Geospatial Research Institute of National Land Survey of Finland and University of Tampere that cooperates with a large network of partners.