More than 16,000 soil samples and 300,000 measured fungal threads produced the first global map of mycorrhizal networks, showing their highest densities under wild grasslands rather than tropical rainforests.
The model estimates the underground web spans about 110 quadrillion kilometers in topsoil and links with roughly 70% of the world’s plants, trading water and nutrients for sugars.
Wild grasslands hold an estimated 40% of all such fungal life, with especially dense networks in cold and flooded grasslands including the Tibetan Plateau and wetlands in Florida and South Sudan.
Large farms showed thread densities about half those of untouched land, and converted grassland was nearly 50% sparser, though the study could not isolate whether plowing, fertilizer or fungicides drive the loss.
The findings could reshape conservation priorities because these fungi pull about 3.6 billion metric tons of CO2 into soil each year, while earlier analysis found 95% of the richest sites lie outside protected areas.
Earth's fungal hotspots are in grasslands vanishing four times faster than forests. Is it too late to save them?
Can we save the planet with fungi that might also poison our food with toxic 'forever chemicals'?
Unveiling the Underground: 2026 Global Mapping of Arbuscular Mycorrhizal Fungi and the Urgent Need for Protection
Overview
In June 2026, scientists published the first global map of Earth's arbuscular mycorrhizal (AM) fungal networks, revealing their vast scale and importance. This breakthrough made the invisible world beneath our feet visible, as experts highlighted how it fills a major knowledge gap. For years, the true extent and distribution of these underground networks were unknown, but the new research shows they are a vital part of our planet’s ecosystems. By mapping these fungi, which form symbiotic relationships with most plants, the study provides crucial insights into their role in supporting life and maintaining environmental health.