Scientists map Earth's vast underground fungal network for first time

A new scientific study has revealed the Earth’s underground fungal network is far larger than previously thought. Researchers found that if all the fungal threads beneath the ground were stretched into a single line, they would extend about 110 quadrillion kilometers, enough to cover nearly 10% of the width of the Milky Way galaxy, as per reports.

The findings come from the first ever global map of underground fungal networks. The study focused on arbuscular mycorrhizal fungi, tiny organisms that live in the soil and form partnerships with most land plants. These fungi help plants absorb important nutrients such as nitrogen and phosphorus from the soil. In return, plants provide carbon to the fungi, creating a relationship that benefits both sides. 

Scientists discovered that the highest concentration of these fungal networks exists in natural grasslands, especially in high altitude and flooded grasslands. Areas such as the Florida Everglades contain extremely dense fungal growth in the top 15 centimeters of soil. Researchers estimate that these grasslands hold around 40% of the world's fungal biomass. These underground fungal networks play a major role in storing carbon and helping fight climate change.

Previous estimates suggest that these fungi absorb around 3.9 billion metric tons of carbon dioxide every year, which is equal to about 11% of global fossil fuel emissions recorded in 2021. 

To create the first global map of fungal density, scientists collected information from 16,669 soil samples gathered through 322 different studies. The samples came from every continent and covered nine different ecological regions.

Researchers then used artificial intelligence to analyze the data and predict fungal distribution across Earth's land surface. The study found that the average density of fungal threads in topsoil is about 4.4 meters per cubic centimeter.

Natural grasslands showed the highest density, averaging 6.6 meters per cubic centimeter, while areas with cultivated trees and intensive farming showed much lower levels of fungal growth.

Lead researcher Justin D Stewart said the findings are changing scientist’s understanding of how life is distributed on Earth. He warned that natural grasslands are disappearing quickly because they are often converted into farmland.

Stewart believes protecting these ecosystems is important because they contain some of the densest fungal communities on the planet.

Researchers also found that agricultural activities may be damaging these underground networks. Cropland soils contained about 50% fewer fungal threads than natural ecosystems.

The use of chemical fertilizers, fungicides, and other intensive farming methods may reduce the need for plants to depend on fungi.