Burn and Bloom: The Hidden Role of Fungi in Fire Recovery
New studies on fungal responses to the natural cycle of forest fires.
“Only you can prevent wildfires.” - Smokey Bear
Not all fires are created equal, especially when it comes to ecosystem management. The Intermediate Disturbance Hypothesis suggests ecosystems thrive with a certain level of natural disturbance—something wildlife has had time to adapt to. Just as trees need some wind to grow strong, ecosystems benefit from periodic natural fires. However, while human-caused fires and those worsened by climate change must be mitigated, stopping all fires can lead to dry brush buildup, setting the stage for even more devastating blazes. So, while Sequoia Trees get all the attention for their fire-germinating seeds, let’s take a look at how the fungus take to the ashes.
“Give a hoot! Don't pollute.” - Woodsy Owl, less problematically.
Historically, there was a time when fallen trees accumulated because no fungi could decompose their bark. This buildup of fuel in a high-oxygen environment led to catastrophic, uncontrollable fires. The intensity of modern fires depends largely on the amount of flammable material present, where fungi—whether as mutualists, decomposers, or pathogens—play a crucial role by influencing tree growth, water retention, and decay. Meanwhile, while forest vegetation may take only a few years to recover after a fire, the impact on fungi can linger much longer, revealing the delicate balance they maintain in post-fire ecosystems.1, 2, 3, 4
Fungi in fire-affected ecosystems can be broadly classified into five overlapping categories:
Pyrophilic fungi are equipped with heat-resistant traits, including durable spore coats.
Fire-avoidant fungi find niches safe and hidden away from the passing fire (inside fallen trees, in plant roots, and within deeper soils).
Fire-responsive fungi capitalize on nutrient surges and ecological shifts (such as a reduction of competition and predation) that follow a fire. However, if a fire becomes too large, nutrient availability may decline compared to initial levels.
Fire-adapted fungi are specifically evolved to thrive in post-fire environments, with traits tailored to these conditions.
Opportunistic dispersers quickly colonize newly available habitats in the aftermath of a fire (some possibly utilizing smoke as a transportation asset).
Fire resistant traits stem from “membrane lipid composition [fluid cell walls], cell membrane thickness, hyphal characteristics, and cell size” while “chemical or physiological traits like melanin synthesis [in cell walls] (UV resistance), heat shock response (oxidative stress resistance), nutrient acquisition (utilization of post-fire nutrient flushes), and other pathways help fungi survive temperature and ecological stressors common during and after the fire” (Hopkins et al. 2024). Surrounding soil additionally helps act as a fire insulant for fungi deep enough underground.1
The opportunistic dispersers often venture into surrounding areas after a fire. While some fungi thrive in the disturbed environment, these others face challenges due to the absence of plant hosts. Those that do remain play a crucial role in replenishing nutrients, supporting plant regrowth in the recovering ecosystem.1
Although many fungal species have adapted to withstand wildfires, studies in pine forests show that fungal diversity remains higher in unburned soils.3 Additionally, research in a taiga biome found that most fungi persisting after a fire maintained symbiotic relationships with their environment.4
While fungi are often overlooked in discussions of fire recovery, understanding their ability to adapt, survive, and support regrowth can help navigate the challenges of climate change and increasing wildfire intensity.
References
1. Hopkins, J. R., & Bennett, A. E. (2024). Leveraging traits for insight into the fungal ecology of burned ecosystems. Ecosphere, 15(11), e70008.
2. Fox, S., Sikes, B. A., Brown, S. P., Cripps, C. L., Glassman, S. I., Hughes, K., ... & Jumpponen, A. (2022). Fire as a driver of fungal diversity—A synthesis of current knowledge.
3. Lazarević, J., Topalović, A., & Menkis, A. (2024). Fungal Diversity in Fire-Affected Pine Forest Soils at the Upper Tree Line. Forests, 15(11), 2012.
4. Cheng, Z., Wu, S., Pan, H., Lu, X., Liu, Y., & Yang, L. (2023). Cortinarius and Tomentella Fungi Become Dominant Taxa in Taiga Soil after Fire Disturbance. Journal of Fungi, 9(11), 1113.
Photo Credit
Forest Photo: Brewbooks, near Seattle, USA, CC BY-SA 2.0
Chaetomium: Keisotyo, CC BY-SA 3.0
