Jonas Rönnberg

I am an Associate Professor in Forest Management and have worked at the Swedish University of Agricultural Sciences (SLU) since the mid-1990s, with a primary focus on forest damage, root rot, and biological control in boreal forestry. My research centres on the epidemiology, biology, and management of Heterobasidion, one of the most economically important pathogens in northern coniferous forests. I completed my PhD in 1999 on the occurrence and development of root rot across multiple generations of Norway spruce, and I have since worked extensively with infection ecology, disease dynamics, timber losses and practical control methods.

Since 2021, I have served as Head of the SLU Forest Damage Centre, where I work to strengthen, coordinate, and communicate Swedish and Nordic research on forest damage and climate-related risks. I also have long-standing experience in academic leadership; between 2008 and 2019, I was Vice Dean of the Faculty of Forest Sciences with responsibilities including international affairs, environmental monitoring, and gender equality.

I have been deeply involved in Nordic research collaboration for many years, including serving as leader of the joint Nordic Secretariat for SNS (Nordic Forest Research) and NKJ (Nordic Joint Committee for Agricultural and Food Research), operating under the Nordic Council of Ministers. These roles have enabled me to work strategically with research programmes, networks, policy development, and stakeholder engagement across the Nordic region. Internationally, I have served since 2015 as Coordinator of the IUFRO Working Party on root and butt rots.

At the national level, I am a long-standing board member of Föreningen Skogen, where I contribute forest research perspectives to discussions on forest policy, practice, and sector development. I am also part of the national support group for the Swedish National Forest Research Agenda, helping to identify and articulate long-term research needs in collaboration with academia, agencies, and industry. In addition, I participate in SIFI, the Swedish forest sector’s strategic think tank, where researchers and industry stakeholders jointly explore emerging challenges and opportunities.

My research is broad and application-oriented, spanning pathogen biology, resistance and susceptibility, forest management impacts, risk modelling, remote sensing and innovative methods for early detection of forest damage. I have led and contributed to numerous research projects funded by Formas, the Swedish Forest Society Foundation, the Swedish Energy Agency, forest companies, and national stakeholders. My work has included studies of treatment effects, seasonal infection patterns, multi-species interactions, use of drones and sensor-based technology, and alternative biological control strategies including antagonistic fungi and naturally occurring mycoviruses.

Teaching and knowledge dissemination have always been integral to my role. I have taught extensively at undergraduate, master’s, and doctoral levels at SLU and internationally, including in Canada and China. I have also organised numerous field courses, excursions, and professional training activities. I aim to bridge scientific understanding with practical forestry, and to communicate complex topics in ways that support both evidence-based decision-making and long-term forest resilience.

Overall, I am driven by the ambition to understand how forest damage systems function, how climate change influences risks, and how research can contribute to sustainable, resilient forestry. I work to ensure that scientific insights become useful for practitioners, policymakers, and forest owners, and that we collectively advance the future of Nordic and European forest health.

My research focuses on forest damage, with a particular emphasis on Heterobasidion root rot and how this pathogen affects the productivity, ecology, and long-term resilience of Nordic forests. Throughout my career I have worked to understand the biology, epidemiology, and spread of root rot, and how we can best monitor, prevent, and reduce its impact through forest management and new control methods.

Epidemiology, biology and spread of root rot
I have spent many years studying how Heterobasidion infects and spreads within and between stands of Norway spruce and Scots pine. This includes research on stump infection, spore dispersal, root contacts and disease progression across multiple forest generations. A recurring theme in my work is the interaction between forest management, stand structure, climate factors and the resulting risk of disease development.

Through field experiments, laboratory studies and modelling approaches, I aim to describe how the pathogen behaves under different ecological conditions and how infection levels affect timber production, forest health and economic outcomes.

Biological control and alternative treatment methods
A major part of my research concerns biological and chemical control methods for reducing root rot. This includes studies on the performance of Phlebiopsis gigantea (Rotstop) and urea, as well as newer alternatives such as bacterial agents and mycovirus-based control strategies.

My work covers:

• treatment efficacy in different seasons and forest types
• competition dynamics between pathogens and antagonists
• practical aspects of treatment application
• cost-effectiveness, ecological impact and long-term sustainability

The current development of mycovirus-based control is particularly promising. Together with colleagues, I study naturally occurring viruses capable of reducing the pathogenicity of Heterobasidion, aiming to provide a future biological tool with long-term and environmentally sound potential.

Monitoring, modelling and risk assessment
Another key component of my research is the development of tools and methods for detecting and predicting forest damage. This includes:

• epidemiological models for infection risk and disease progression
• analyses at stand and landscape scales
• identification of climate-driven risk factors
• estimation of long-term timber losses and management consequences

These studies support the development of decision-support systems that help forest managers adapt to increased abiotic and biotic risks under climate change.

New technologies for early detection
I have led and contributed to projects developing innovative detection techniques, such as:

• drone-based and remote-sensing methods
• camera, spectral and sensor technologies
• trained detection dogs for forest health monitoring
• digital tools and systems for forest damage surveillance

These approaches aim to enable earlier and more accurate detection of forest damage, allowing for timely and cost-effective interventions.

Forest management, climate change and resilience
A central theme in my research is how forest management can reduce susceptibility to damage. My work addresses:

• how thinning, rotation length and species selection influence disease risk
• how climate change alters damage dynamics
• the role of mixed stands, improved planting material and alternative species
• strategies for strengthening forest resilience at stand and landscape levels

This part of my research connects biological knowledge with practical forestry and long-term planning.

Collaboration and applied research
Collaboration with the forest sector, authorities and industry partners is an essential part of my work. I have led and participated in numerous projects funded by Formas, the Swedish Forest Society Foundation, the Swedish Energy Agency, large forest companies and other organisations.

My ambition is to ensure that research results contribute directly to practical recommendations and sectoral decision-making, and that new scientific insights support a sustainable and resilient Nordic forestry.

I have taught at the Swedish University of Agricultural Sciences (SLU) for more than two decades, primarily within forest pathology, forest management, forest health and applied field-based analysis. My teaching spans undergraduate, master’s and doctoral levels, and I have also taught internationally in Canada and China.

Courses and teaching areas
Over the years, I have contributed to a wide range of courses related to forest health and forest management. My teaching has included topics such as:

• root rot and major forest pathogens
• diagnosis and monitoring of forest damage
• epidemiology and infection processes in forest ecosystems
• forest management practices linked to risk reduction
• timber loss assessment and economic consequences
• preventive measures and control strategies in forestry

I have also taught in courses involving forest ecology, sustainable forestry, forest planning and environmental monitoring. My teaching often integrates lectures with laboratory sessions and field exercises, allowing students to develop diagnostic skills, analytical abilities and practical understanding.

Field courses and excursions
A substantial part of my teaching is field-based. I have led numerous excursions and field days focusing on:

• diagnosing forest damage and assessing root rot
• stand-level analysis and risk evaluation
• practical aspects of control methods used in forestry
• forest management under climate and disturbance pressures

Field-based learning is central to my pedagogical approach, as it helps students connect theoretical knowledge with real-world forest conditions. Many of these activities are conducted together with forestry companies, agencies and other practitioners.

Supervision
I have supervised several bachelor’s and master’s theses in forest pathology, forest health and forest management, often in collaboration with partners in the forest sector.

I have also supervised PhD students and participated in doctoral committees, serving as examiner, opponent and member of evaluation panels.

Teaching philosophy
My teaching is grounded in the idea that students learn best when scientific depth is combined with practical insight. I aim to:

• connect research results to real forestry challenges
• encourage analytical thinking and evidence-based reasoning
• integrate field-based, experiential learning with classroom instruction
• foster a supportive and inclusive learning environment
• help students develop both biological understanding and practical competence

I believe that the complexity of forest health issues becomes most clear when students can observe, analyse and discuss problems directly in the field.

International teaching experience
I have taught courses and guest lectures internationally, including at the University of Northern British Columbia (Canada) and at forestry universities in Nanjing and Harbin, China. These experiences have enriched my teaching and provided broader perspectives on forest health, management systems and global disturbance dynamics.