Tree Pathogens & Climate Change: How Phytopathology is Driving Forest Resilience

Forests are described as the lungs of the Earth—absorbing carbon dioxide from the atmosphere and releasing oxygen through photosynthesis at a massive scale. But today, climate change is reshaping our world’s natural ecosystems. As a result, forests are facing unprecedented health risks.

Dr. Nicolas Feau, a forest pathologist with the Canadian Forest Service at the Pacific Forestry Centre in Victoria, British Columbia, and an adjunct faculty member in the University of British Columbia’s Department of Forest and Conservation Sciences, is at the forefront of understanding and combating these challenges.

“As our environment changes, fungi that were once balanced within forest ecosystems are becoming more aggressive, and they’re impacting trees more severely each year,” Feau explains, highlighting how these shifts threaten the equilibrium of forest ecosystems.

His research is focused on tree pathogens—specifically fungi—and is driving important discoveries that mitigate existing threats and predict what’s next on the horizon, allowing for preventative solutions to help preserve our world’s forests for the future.

A Forest Pathologist’s Mission

Feau’s fascination with trees began in childhood, when he spent time gathering mushrooms in the forest with his parents. His early love for nature evolved into his current career dedicated to understanding the complex dynamics between trees and the pathogens that threaten them.

Unlike agricultural pathologists, forest pathologists like Feau work on a larger scale, studying ecosystems where time and size amplify challenges. Trees are long-lived organisms that respond differently to pathogens compared to crops. This requires innovative approaches to research.

“My research aims to understand the interaction between trees and pathogens,” Feau explained. “This includes studying individual interactions, population-level dynamics, and how larger environmental factors like climate change influence these relationships.”

The Role of Climate Change

Forests face growing threats from tree diseases, many of which were once balanced within their ecosystems. Feau points to fungi that, for centuries, coexisted with trees without causing significant harm. Today, rising temperatures and shifting weather patterns have disrupted this equilibrium, modifying pathogen life cycles and increasing their virulence.

One striking example is Nothophaeocryptopus gaeumannii, the fungus responsible for Swiss needle cast disease in Douglas-fir trees, which affects the coastal forests of the Pacific Northwest. In recent decades, changing environmental conditions have contributed to periodic epidemics of Swiss needle cast, first observed along the Oregon coast and now spreading to higher latitudes in Canada.

“Climate change is altering everything, from tree health to pathogen biology,” said Feau. “We’re now seeing diseases emerge and spread in ways we haven’t encountered before. Forests are resilient, but these changes are testing their limits.”

From Forests to Labs: Innovative Research Approaches

Feau’s fieldwork provides invaluable insights into the early stages of infections, but translating those findings into actionable strategies requires controlled experimentation. That’s where the lab—and advanced equipment like plant growth chambers—play a vital role.

For example, Feau plans to use Conviron plant growth chambers to study pathogens in Douglas fir seedlings, under controlled temperature, humidity, and light settings.

“The seedlings we use in plant growth chambers are one to two years old,” Feau explained. “We keep them in a one-gallon pot and maintain the temperature at 20 degrees Celsius. The seedlings are set to experience 16 hours of daylight and 8 hour nights, and we keep them for months, or even more than one year, before they show symptoms.”

In addition to allowing researchers to control conditions that are important for the success of the infection of the tree by the pathogen, like temperature and humidity, the plant growth chambers ensure consistency across long-term experiments like the one Feau describes, critical to achieving reliable outcomes over time.

Uncovering Genetic Insights

A significant part of Feau’s research focuses on identifying the genetic mechanisms that make certain trees resistant—or vulnerable—to pathogens. After observing infected seedlings in the chambers, his team conducts genomic and transcriptomic analyses to pinpoint specific genes involved in resistance or susceptibility.

“We infect plants, observe their responses, and then sample their DNA and RNA to find resistance genes,” he explains. “This information can guide forestry practices by helping us identify rapidly and more efficiently tree populations that are more likely to thrive in future climates.”

This genomic approach enhances our understanding of tree-pathogen interactions and provides practical tools for managing forest health. Forestry managers, for example, can use research insights to prioritize planting more resilient tree species, thus ensuring greater long-term forest sustainability.

The Bigger Picture: Why It Matters

The implications of Feau’s work extend far beyond academia. Forests are critical to biodiversity, carbon sequestration, and industries like timber and tourism. As climate change accelerates, maintaining healthy forests is becoming increasingly vital—not just for ecological reasons but also for economic and social stability.

One of the most pressing challenges is the globalization of trade, which facilitates the spread of pathogens. Wooden shipping crates, for instance, can harbor fungal spores that travel across continents, introducing new diseases to previously unaffected regions. Feau emphasizes the need for better detection tools and management strategies to combat these threats.

“Prevention is key,” he says. “By developing tools to detect pathogens early and understanding how they interact with trees, we can mitigate their impact before they cause widespread damage.”

A Glimpse Into the Future

Looking ahead, Feau is optimistic about the role of phytopathology in addressing forest health challenges. Tools like CRISPR and molecular biology techniques offer unprecedented opportunities to explore tree genetics and pathogen interactions. Advancements in controlled environment research too will remain indispensable to Feau’s work and other research like it.

As forests face new challenges, Conviron’s plant growth chambers provide a way for Feau’s team to bridge the gap between fieldwork and lab studies, replicating natural conditions so that scientists can predict what will happen in the forest on a larger scale.

“These tools are powerful for testing our hypotheses,” Feau noted. “They’re helping us make such great advances, and save so much time. With CRISPR, for example, I could validate a candidate gene for resistance to specific pathogens in just a couple of weeks. The traditional way would take much longer, and advancements would be slower.”

On the cutting edge of advancements in his field, Feau and his team are performing research that will preserve our forests and their much-needed resources for future generations.