Changing climate creates new threats: “Our trees are not ready to fight back”

Knowledge about the importance of microbial communities for the health of forest trees has increased significantly in recent years and is documented in books, articles, and databases.

Forestry is one of Linnaeus University’s areas of strength, where researchers study everything from raw materials and timber construction technology to digitalisation and forest management.

Healthy and vital forests are crucial both for biodiversity and for our ability to tackle the climate crisis. At the same time, the amount of forest damage caused by fungi, insects, cloven-hoofed game, and drought is increasing. With the help of digital tools, there are ways to protect the forest and identify problems before it has gone too far.

– It’s important that we detect damage as early as possible in order to take cost-effective action, and digital solutions are crucial in this, says Johanna Witzell, professor of forest health at the Department of Forestry and Wood Technology.

Forest by chance

According to Johanna herself, it was actually a bit of a fluke that her research ended up being about forestry and forest damage.

– Several exciting opportunities came up that led me down the forestry path. I completed my PhD in Biology in Finland with a thesis on fungal damage to fast-growing trees. It sparked a fascination and curiosity in me to delve deeper into the subject, to try to understand and create something new.

Previously, Johanna focused primarily on how trees and forest plants defend themselves chemically against attackers. Now, her research is more focused on how microbial communities can influence trees’ resilience to pests.

Microbes are important for tree health

Microbe communities are a composition of different kinds of organisms, such as fungi and bacteria. Just as gut bacteria are important for our health, bacteria and fungi living inside trees can be important for tree health.

– It’s an exciting field of research that’s becoming increasingly relevant, partly due to climate change, which is leading to altered precipitation patterns and rising temperatures. This, in turn, increases the risk of things like large-scale disease epidemics and insect outbreaks.

– A changing climate creates favourable conditions for common pests such as harmful fungi and insects, and at the same time, completely new ones spread and establish themselves. Our trees are not ready to fight back. Stressed and damaged trees have a reduced capacity to store carbon.

Johanna says that it is difficult to rank the pests, but that bark beetles, root rot, and grazing damage are among the more common. At the same time, there are new, foreign pests that have not been present in Sweden before, and their impact may increase.

She emphasises that it is particularly important to be vigilant when it comes to damage to pine, a tree species that is of great importance to both forestry and biodiversity. Trees such as elm and ash are also severely affected by foreign fungi.

– These tree species are not as economically valuable as pine and spruce, but they are important from an ecological and cultural perspective. We have a collaborative project with Skogforsk and the Swedish University of Agricultural Sciences aimed at gaining knowledge on how we can preserve the elm, which is critically endangered. We are trying to learn how we can work with the remaining elms, and the hope is to be able to propagate the trees that show resistance to Dutch elm disease.

Protecting trees in urban environments

Another project Johanna is involved in, Urban Tree Guard, is a European network project focused on how trees in urban environments can be protected from new pests.

– I really enjoy international collaborations. In this project, we are researchers from over 40 countries working together, and it’s interesting to see how different countries and cultures approach the challenges surrounding forest damage.

By using advanced sensors, drones, and satellites, damage and stress in trees can be detected and analysed at an early stage. This makes it possible to take action and prevent the damage from spreading further.

Digital tools for support

At Linnaeus University, there is collaboration between the Department of Forestry and Wood Technology and the computer science subject group. Together, they are working to develop digital tools that can help identify and manage forest damage.

– An example is using cameras and other kinds of sensors in nurseries in the future, to be able to quickly scan a vast number of plants and detect early signs of damage. If you only use your eyes, you will notice them only later, by which point they will have spread further.

One method for studying tree-dwelling fungi is to try to capture them on nutrient media in the laboratory.

– Drones can be used to monitor both individual trees and large forest areas. We have invested a lot in this and have built up a substantial drone fleet. We also work with satellite data, which can provide an even broader overview.

A unique mobile forest lab

Together with colleagues at Linnaeus University, Johanna has also established a mobile forest laboratory called ForestEdge, which started operating in 2023.

– When I first came here, there was no lab for the research that I and others using similar technology conduct. A common solution is to find or build a space, but we realised that that would take a long time and be expensive. My idea was to have a modular and mobile infrastructure instead. Most of our instruments are portable, including tools for performing DNA analysis on-site in the forest.

– The flexible infrastructure has many advantages compared to traditional laboratories and can expand and evolve more easily over time. It also provides unique opportunities for collaborative projects, such as between myself, working on damage, and other researchers working on genetics.

Johanna describes the forestry research environment at Linnaeus University as very dynamic, with many opportunities. Collaborations around digital tools are just one of these.

– That we’re doing the right things is clear from the international response. We’ve received new funding from the EU, as partners in larger projects, which we’re very happy about.

A dynamic research environment

Johanna once again stresses how incredibly passionate she is about her job. Her commitment stems from a deep care for nature and a concern about the way things are going.

– We humans cause a lot of destruction, which is why it feels meaningful to be able to delve into, try to understand, and contribute to finding solutions that can instead benefit forest health.