An extensive network of microscopic fungi, estimated to stretch 110 quadrillion kilometers across Earth’s topsoil, has been mapped by an international study. This vast underground system, composed of arbuscular mycorrhizal fungi (AM fungi), plays a critical role in supporting plant life, storing carbon, and maintaining ecosystem health.
The findings, led by researchers associated with the Society for the Protection of Underground Networks (SPUN), utilized over 16,000 soil samples and advanced computer modeling. The study revealed that the collective length of these fungal threads, known as hyphae, is immense, though it does not represent a single, planet-spanning organism. Instead, it is the sum of countless interconnected networks spread globally.
A Hidden System Supporting Life
AM fungi form a symbiotic relationship with approximately 70% of all land plants. In this partnership, plants provide sugars produced through photosynthesis to the fungi, while the fungi help plants absorb essential water and nutrients like phosphorus and nitrogen from the soil. These fungal threads extend beyond plant root systems, acting as an extension that allows plants to access resources otherwise out of reach. Scientists believe these fungi were instrumental in plants colonizing land around 475 million years ago.
Often referred to as the “wood wide web,” these fungal networks connect multiple plants, facilitating the movement of nutrients, water, and chemical signals. This interconnectedness allows plants to potentially share resources or signal distress. The health of these underground systems is considered fundamental to the survival of many plants and the stability of entire ecosystems.
Climate Change and Agriculture Concerns
The study highlighted the significant role of these fungal networks in carbon storage. It is estimated that Earth’s topsoils hold about 300 megatons of carbon within these fungal structures, a quantity several times the total mass of all humans. The fungi also aid in moving carbon from plants into the soil. Some estimates suggest these networks sequester up to one billion metric tons of carbon annually, making them a natural ally in combating climate change by keeping carbon out of the atmosphere.
However, the research also identified signs of decline, particularly in agricultural lands. Intensely farmed areas showed significantly lower fungal network concentrations, up to 50% less than in undisturbed natural ecosystems. Practices such as deep tilling, excessive fertilizer use, and soil disturbance can damage these vital fungal communities. This reduction can make crops more reliant on synthetic fertilizers and less resilient to environmental stresses like drought.
Future Implications
The newly created global map is expected to help identify areas requiring protection and restoration for these fungal networks. Safeguarding these hidden ecosystems could enhance food security, improve plant resilience, reduce the need for fertilizers, and boost carbon storage. Researchers emphasize that conservation efforts have historically overlooked this crucial underground biological infrastructure, which underpins much of life on Earth.
Steve Lopez is the Editorial Page Editor for News Raise. He covers Health. He has won more than a dozen national journalism awards for his reporting and column writing at seven newspapers and four news magazines.
