If you are Czech, or have visited Czech forests in summer, you have probably met keen mushroom foragers. These early morning forest dwellers roam the woods after rain, filling baskets with boletes, chanterelles and other edible species, while admiring the familiar, if untouchable, red and white Amanitas. All of these mushrooms are only short-lived fruiting bodies of a much older organism living hidden in the forest soil.
The Pioneers of Land
For a long time, biology textbooks treated fungi as odd plants with unusual flowers. That view only shifted in 1969, when Robert Whittaker proposed his five kingdom classification and formally recognised fungi as their own kingdom (Whittaker, 1969). We now also know that fungi are far older than land plants. Recent research suggests fungi appeared between 900 million and 1.4 billion years ago, hundreds of millions of years before plants colonised land (Szánthó et al., 2025).
When plants finally did move onto land, fungi were already there. Together they formed an intimate partnership between roots and fungal filaments called mycorrhiza, from the Greek for “fungus” and “root”. In this relationship, plants trade carbon for nutrients and water supplied by the fungus, which can increase plant growth and stress tolerance (Smith & Read, 2008). Today, majority of vascular plant species rely on some form of mycorrhizal association, which means this ancient alliance underpins almost all terrestrial ecosystems (Brundrett & Tedersoo, 2018).
A Partnership Under Stress
This is the relationship at the heart of our research. We focus on three of the most important Central European tree species — spruce, beech and oak — and sample their forest soils. From these samples we measure root traits and the degree of mycorrhizal colonisation. We compare these “below ground” indicators with signs of climate stress “above ground”, such as canopy defoliation, disease symptoms and growth decline. At the same time, we monitor physiological and environmental parameters — tree increment, sap flow, soil water potential, soil temperature and humidity.
Another part of the project brings us closer to those mushroom foragers. Throughout the growing season we systematically survey macromycetes — the larger, visible fungi — by recording the fruiting bodies that appear on our research plots. These observations give us clues about how fungal communities shift over the year and how this relates to the health of the trees. To complete this picture, we analyse the molecular composition of forest soils, looking for fungal DNA from species that do not produce visible mushrooms at the time of sampling.
What do we hope to find? Predominantly, we want to understand how this old partnership between trees and fungi behaves under present-day climate change. Are fungal communities affected mainly indirectly, via stressed trees, or are the fungi themselves directly sensitive to changing climate parameters? Can we help forests cope with climate change by supporting their fungal partners, for example by developing mycorrhiza promoting substrates for seedlings in nurseries? Some experimental trials in this direction already exist, but their results are still mixed.
The questions are many, and although mycorrhiza has been shaping life on land for hundreds of millions of years, our quest to understand this hidden network — and to use that knowledge for the benefit of future forests — is only just beginning.
References
Brundrett, M. C., & Tedersoo, L. (2018). Evolutionary history of mycorrhizal symbioses and global host plant diversity. New Phytologist, 220(4), 1108–1115. https://doi.org/10.1111/nph.14976
Smith, S. E., & Read, D. J. (2008). Mycorrhizal symbiosis (3rd ed). Academic Press.
Szánthó, L. L., Merényi, Z., Donoghue, P., Gabaldón, T., Nagy, L. G., Szöllősi, G. J., & Ocaña-Pallarès, E. (2025). A timetree of Fungi dated with fossils and horizontal gene transfers. Nature Ecology & Evolution, 9(11), 1989–2001. https://doi.org/10.1038/s41559-025-02851-z
Whittaker, R. H. (1969). New Concepts of Kingdoms of Organisms: Evolutionary relations are better represented by new classifications than by the traditional two kingdoms. Science, 163(3863), 150–160. https://doi.org/10.1126/science.163.3863.150
Link to original article on Medium: https://medium.com/ph-d-stories/the-billion-year-old-secret-beneath-our-feet-can-fungi-save-our-forests-a3d7d2784fce