Scientists Map Hidden Fungal Web Under 70% of Earth's Plants

The ground beneath your feet holds one of Earth's largest living systems, and scientists just mapped it for the first time.

Mycorrhizal fungi wrap around the roots of 70% of the world's plants, creating an underground web that stretches 68 quadrillion miles. That's nearly a billion times the distance from Earth to the Sun, yet until now, no one knew exactly where it lived or how dense it grew.

Dr. Justin Stewart, an evolutionary biologist at the Society for the Protection of Underground Networks, puts it simply: a single teaspoon of soil can hold up to 32 feet of microscopic fungal threads. The entire network weighs four to six times more than every human on the planet combined.

Researchers gathered over 16,000 soil samples from every continent to train a computer model that maps fungal density across the globe. Dutch scientists filmed over 300,000 living fungal threads with robotic cameras to validate the predictions.

The map revealed something unexpected. Wild grasslands, not tropical rainforests, contain the densest fungal networks on Earth.

These humble grasslands hold an estimated 40% of all this fungal life. The richest concentrations appear in cold and flooded grasslands like the Tibetan Plateau, Florida's Everglades, and South Sudan's wetlands.

The fungi earn their keep through trade. They supply plants with water and nutrients in exchange for sugars made through photosynthesis. A root connected to this network can forage up to 100 times more soil than it could alone.

Why This Inspires

This hidden partnership does more than help individual plants thrive. The fungal network pulls roughly 4 billion tons of carbon dioxide into the soil each year, close to a tenth of what humans emit.

Farmland shows about half the fungal density of wild land. When old grassland converts to farms, the network thins by nearly 50%, possibly due to plowing, fertilizers, or fungicides.

Dr. Toby Kiers, SPUN's executive director, notes that 95% of the richest fungal sites currently sit outside protected areas. Wild grasslands are vanishing into farmland four times faster than forests, yet they remain among the least protected ecosystems.

The raw data is now free to download. Conservation groups can identify the densest fungal ground to protect. Farmers can test gentler methods like no-till planting. Researchers can track how these networks change over time.

For the first time, we can see what's been supporting most life on land all along.