Subterranean fungal networks spanning 110 quadrillion kilometers—nearly 750 million times the distance from Earth to the sun—sustain global plant life and regulate the climate, according to a study published in Science. Researchers from the Society for the Protection of Underground Networks (Spun) utilized machine-learning models and data from over 16,000 soil cores to create the first global map of these arbuscular mycorrhizal fungi, which associate with over 70% of plant species.
How Fungal Networks Regulate Global Climate
Arbuscular mycorrhizal fungi function as a critical biological infrastructure by trading nutrients and water for carbon produced by plants. Lead author Dr. Justin Stewart notes that a single teaspoon of soil can contain up to 10 meters (32 feet) of these tubular hyphae networks. By drawing carbon deep into the earth, these systems act as a natural mechanism for carbon sequestration. Beyond carbon storage, these networks distribute nutrients and shield waterways from chemical runoff, such as nitrogen and phosphorus, according to co-author Dr. Toby Kiers.
Arbuscular mycorrhizal fungi have been forming these symbiotic partnerships for approximately 475 million years, predating most complex terrestrial life.
Why Cropland Density Trails Wild Ecosystems
The study reveals a stark contrast between wild ecosystems and agricultural land. Researchers found that fungal network densities in croplands are 47.3% lower than those in wild environments. Dr. Stewart attributes this decline directly to industrial agricultural practices. Tilling, for example, physically disrupts the delicate hyphal systems, while the application of synthetic fertilizers and fungicides can sever the symbiotic link between plants and fungi. This reduction in density directly limits the soil’s capacity to store carbon and manage nutrient distribution, according to the Spun research team.
Where Are Fungal Networks Most Dense?
Grasslands currently hold the densest hyphal systems globally, according to the mapping data. Specific regions, including the Everglades in Florida, the Sudd flooded grasslands in South Sudan, and global prairie and steppe ecosystems, exhibit “exceptionally high” density. Despite their importance, these regions are often poorly protected and face increasing degradation. The researchers intend to present these findings to policymakers at the upcoming desertification COP in Mongolia to advocate for better land management and conservation of these microbial communities.
Can Agriculture Shift Toward Fungal Collaboration?
Future agricultural trends may prioritize the restoration of soil health over artificial yield boosting. Dr. Stewart argues that current heavy reliance on fertilizers masks the potential for fungi to provide nutrients naturally. By protecting soil microbial communities, farmers could potentially reduce fertilizer dependence while simultaneously enhancing carbon storage. Dr. Merlin Sheldrake, a co-author of the study, suggests that working with these fungal systems is essential to addressing modern challenges, including food security and climate change.
When assessing soil health, look for indicators of microbial diversity. Practices like “no-till” farming and planting cover crops are increasingly recognized as methods to support the expansion of underground fungal networks.
Frequently Asked Questions
What is the primary function of arbuscular mycorrhizal fungi?
These fungi form symbiotic relationships with plants, exchanging essential nutrients and water for carbon, which helps plants grow and aids in long-term carbon sequestration in the soil.
How does tilling affect soil fungi?
Tilling physically breaks the delicate tubular hyphae networks, which significantly reduces the density of the fungal infrastructure and impairs the soil’s ability to store carbon.
Are these fungal networks currently being protected?
Many areas identified with high fungal density, such as specific grasslands and prairies, currently lack adequate protection and are facing ongoing degradation, according to the Spun research team.
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