High-latitude vegetation shifts in the era of global change: Multi-decade ecosystem-level evidence from Northern Europe
Thesis event information
Date and time of the thesis defence
Place of the thesis defence
L2 (Pohjola-sali), Linnanmaa campus
Topic of the dissertation
High-latitude vegetation shifts in the era of global change: Multi-decade ecosystem-level evidence from Northern Europe
Doctoral candidate
Master of Science Petteri Kiilunen
Faculty and unit
University of Oulu Graduate School, Faculty of Science, Geography Research Unit
Subject of study
Geography
Opponent
University Lecturer Heidi Mod, University of Helsinki
Custos
Academy Research Fellow Tuija Maliniemi, University of Oulu
Five decades of vegetation change in Northern Europe
Vegetation in northern ecosystems is changing in response to climate change, but these changes do not occur everywhere in the same way or at the same rate. Monitoring long-term vegetation change is also challenging because datasets spanning several decades are scarce.
The aim of this doctoral thesis is to investigate long-term vegetation change in Northern Fennoscandia and to assess the extent to which these changes correspond to broader vegetation change trends observed elsewhere across northern regions. The thesis examines changes that have occurred over more than five decades across a range of northern vegetation types, from boreal forests to mountain heaths.
The first study demonstrates a decline in the regional diversity of mountain vegetation, as plant communities have become increasingly similar to one another over time. The second study shows that plant communities in heathlands and tundra and in herb-rich forests are less dependent on insect pollination than in the past, and that the availability of pollen and nectar has changed. Both studies highlight the impact of the substantial increase in crowberry on the composition and diversity of mountain vegetation, a phenomenon linked to the broader trend of Arctic shrubification observed across northern regions.
The third study synthesizes existing evidence on long-term vegetation change in Northern Fennoscandia. The review supports the findings of the empirical studies regarding changes in mountain vegetation and reveals structural changes in the northernmost forests, including increasing forest density.
The thesis demonstrates that the vegetation of northern Fennoscandia has changed substantially over recent decades. However, the observed changes do not fully correspond to the vegetation change trends commonly reported across the circumpolar north. The findings highlight the importance of long-term vegetation monitoring and of recognizing regional specificities in vegetation change trends.
The aim of this doctoral thesis is to investigate long-term vegetation change in Northern Fennoscandia and to assess the extent to which these changes correspond to broader vegetation change trends observed elsewhere across northern regions. The thesis examines changes that have occurred over more than five decades across a range of northern vegetation types, from boreal forests to mountain heaths.
The first study demonstrates a decline in the regional diversity of mountain vegetation, as plant communities have become increasingly similar to one another over time. The second study shows that plant communities in heathlands and tundra and in herb-rich forests are less dependent on insect pollination than in the past, and that the availability of pollen and nectar has changed. Both studies highlight the impact of the substantial increase in crowberry on the composition and diversity of mountain vegetation, a phenomenon linked to the broader trend of Arctic shrubification observed across northern regions.
The third study synthesizes existing evidence on long-term vegetation change in Northern Fennoscandia. The review supports the findings of the empirical studies regarding changes in mountain vegetation and reveals structural changes in the northernmost forests, including increasing forest density.
The thesis demonstrates that the vegetation of northern Fennoscandia has changed substantially over recent decades. However, the observed changes do not fully correspond to the vegetation change trends commonly reported across the circumpolar north. The findings highlight the importance of long-term vegetation monitoring and of recognizing regional specificities in vegetation change trends.
Created 2.10.2026 | Updated 5.10.2026