The doctoral dissertation in the field of Forest Entomology, will be examined at the Faculty of Science, Forestry and Technology, Joensuu campus.
What is the topic of your doctoral research? Why is it important to study the topic?
Insect pests such as the European spruce bark beetle (Ips typographus L.; SBB), the most damaging insect pest of Norway spruce (Picea abies (L.) Karst.), have been affected by climate change. Across Europe, large-scale SBB outbreaks have caused severe damage to Norway spruce forests as conditions favorable to outbreaks become more frequent. Although SBB damage in Finland remains lower than in Central Europe, the increasing number of salvage loggings triggered by SBB indicates a rising probability of damage and highlights the need for improved proactive management.
This study evaluated how stand, landscape, and climatic attributes contribute to SBB damage and its spatial distribution in Finland. This research examined differences between damaged and undamaged stands, assessed landscape drivers of new damage, examined spatial clustering and hotspot formation, and developed spatially explicit probability models of SBB damage integrating stand, landscape and climatic variables.
What are the key findings or observations of your doctoral research?
Mature Norway spruce stands characterized by greater age and mean diameter, as well as stands located close to recent clear-cuts, windthrow, or recent SBB damage, showed the highest susceptibility to SBB damage. Stands near recent SBB damage were also more likely to form damage hotspots. Hotspot maps were produced to identify areas of clustered damage and to support forest health management.
Proximity to clear-cuts, mean stand diameter, distance to previous SBB damage, and the number of consecutive days above 25 °C were the strongest predictors of SBB damage. Spatially explicit maps were generated to show the probability of SBB damage at stand level and to identify areas where new damage is more likely to occur or intensify. These results underscore the need for proactive management strategies to address the increasing SBB damage probability under climate change at landscape level.
How can the results of your doctoral research be utilised in practice?
The results indicate that the susceptibility to SBB damage increases as Norway spruce stands mature, particularly under conditions with frequent days above 25 °C. Mature stands not only experience higher damage probabilities but also contribute to the formation and recurrence of damage hotspots, especially when located near previously affected areas. Salvage logging, the typical response to SBB damage, often creates clear-cuts that may promote subsequent damage, as proximity to clear-cuts increases damage probability. The developed probability maps can support forest management by identifying high-risk stands for targeted harvesting, monitoring, and timely intervention. Over the longer term, SBB damage probability will largely depend on forest structural and compositional diversity.
What are the key research methods and materials used in your doctoral research?
The study covered the southern half of Finland, comprising 11.4 million ha of forest land used for wood production. I used two publicly available spatial datasets for privately owned forests provided by the Finnish Forest Centre. Forest-use notifications from forest owners were used to identify harvesting operations, including salvage logging following wind or SBB damage, and served as a proxy for disturbance-related harvests. These data represent the only nationwide, spatially explicit record of salvage logging in Finland.
The second dataset provided stand-level forest structure information derived from remote sensing and field inventories. Differences between SBB-damaged and undamaged stands were examined using chi-squared and Mann–Whitney U tests. Generalized linear mixed-effects models assessed the effects of landscape attributes on the occurrence of new SBB damage, hotspot formation, and the probability of stand-level damage. Damage hotspots were identified using Local Moran’s I.
The doctoral dissertation of John Alexander Pulgarín Díaz, MSc, entitled Contribution of stand, landscape and climatic attributes to Ips typographus damage and its spatial distribution in Finland will be examined at the Faculty of Science, Forestry and Technology, Joensuu campus. The opponent will be Professor Tomáš Hlásny, Czech University of Life Sciences Prague (CZU), Czech Republic, and the custos will be Associate Professor Olli-Pekka Tikkanen, University of Eastern Finland. Language of the public defence is English.
For further information, please contact:
John Alexander Pulgarín Díaz, [email protected], tel. +358 46 539 1920
