Recently, a team has developed the world’s first interactive global map of arbuscular mycorrhizal fungal networks. This represents a colossal project that unveils the extent and biomass of an underground fungal infrastructure essential to life on Earth and to climate regulation, among other things. The scientists are expected to present their map at upcoming United Nations summits with the goal of changing current global soil conservation policies.
The astonishing reach of mycorrhizal networks
For clarity, arbuscular mycorrhizal fungi (AMF) are microscopic soil fungi living in symbiosis with the roots of 70 to 80% of land plants. This symbiotic partnership enables fungi to receive sugars produced by the plants through photosynthesis. The plants themselves also benefit, as fungi help roots absorb water and minerals from the soil more efficiently. Most importantly, these fungi form networks that are often described as the “underground internet of forests” (the Wood Wide Web). With activity dating back at least 475 million years, these networks would have greatly contributed to the colonization of land by plants.
On June 11, 2026, an international team of researchers led by the Amsterdam Institute for Life and Environment (A-LIFE) published their latest findings in Science. These scientists achieved the first ever interactive global map of arbuscular mycorrhizal fungal networks, an enormous project that reveals their remarkable extent. The map is available on the website of the Society for the Protection of Underground Networks (SPUN), a global nonprofit scientific initiative.
“Using more than 2.8 billion fungal DNA sequences from soil samples collected in 130 countries, we created the first high-resolution maps that allow us to predict arbuscular mycorrhizal fungal biodiversity at a 1 square kilometer (km²) resolution across the planet.”, reads the project’s descriptive page.
A map revealing critical soil vulnerabilities
The researchers estimated the total length of fungal filaments present in surface soil at 110 quadrillion kilometers, equivalent to about a billion times the distance from the Earth to the Sun. They also quantified the carbon stored in these mycorrhizal networks at 300 megatonnes of carbon—ranging from four to six times the combined mass of all humanity. Moreover, the density is staggering: a teaspoon of soil can harbor up to ten meters of filaments.
By virtue of its symbiotic relationship with plants, the Wood Wide Web greatly contributes to the stability of life on Earth and to climate regulation. Yet the global map highlights several critical vulnerabilities to human activity. In intensively cultivated regions, the density of mycorrhizal networks is about half what is seen in wild ecosystems. The culprits are mechanical tillage, as well as the use of fungicides and chemical fertilizers. Furthermore, meadows alone account for no less than 40% of the world’s fungal biomass, notably in areas such as the Florida Everglades, the floodplains of South Sudan, and the Tibetan Plateau. Regrettably, these vital zones are underprotected and, worse still, being converted into farmland four times faster than forests.
Finally, the researchers plan to present their map to governments at upcoming United Nations summits. The objective is to finally incorporate mycorrhizal networks into global conservation policies—primarily the worldwide “30×30” agreement—on par with plants and animals. This crucial outreach will be conducted notably by Toby Kiers, an evolutionary biologist and recipient of the 2026 Tyler Prize for Environmental Science.
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