Diseased oak tree bark showing bleeding symptoms. Photo: Daniel Knapp

Project: Acute oak decline in Sweden – Microbial contributors and factors across geography and seasons

This project aims to characterize bacterial and fungal microbiomes, along with ectomycorrhizal (EcM) communities and Phytophthora species, associated with symptoms of acute oak decline (AOD) in Sweden. By comparing declining and vital pedunculate and sessile oaks across sites and seasons, we will identify microbial patterns and risk factors relevant for monitoring oak health and provide knowledge that supports applied forestry, future breeding programs and management.

Project information

Project manager
Daniel Knapp
Other project members at Linnaeus University
Johanna Sunde, Johan Kroon, Johanna Witzell
Participating organizations
Linnaeus University, Skogforsk
Financier
Stiftelsen Konsul Faxes Donation
Timetable
2026–2028
Subject
Forestry and wood technology (Department of Forestry and Wood Technology, Faculty of Technology), environmental science (Department of Biology and Environmental Science, Faculty of Health and Life Sciences)
Research group
The Bridge

More about the project

Acute oak decline (AOD) is an emerging disease complex that threatens European oak forests. While well studied in the United Kingdom and parts of continental Europe, knowledge is lacking in Sweden, where both pedunculate (Quercus robur) and sessile oak (Q. petraea) are important species.

This project will expand our understanding about AOD in Sweden by sampling diseased and healthy oaks across several sites and seasons. From bark and rhizosphere samples, we will assess bacterial and fungal communities and Phytophthoraspecies using long-read sequencing for DNA metabarcoding, complemented by culture-based techniques.

The expected outcome is the first integrated dataset on AOD-associated microbes and factors. These results will clarify how microbial communities differ along trees, seasons and across environments. This knowledge will be directly relevant for monitoring disease, informing forest managers, and providing a scientific basis for future oak breeding and health strategies.

The project is part of the research group The Bridge.