A new scientific paper published in the journal Science estimates that underground networks of arbuscular mycorrhizal fungi stretch across 110 quadrillion kilometers worldwide. These networks, which partner with nearly three-quarters of plant species, move about 4 billion metric tons of carbon each year.
Researchers used machine learning models trained on thousands of soil samples to create global maps of the fungi. The networks help plants absorb water and nutrients in exchange for carbon drawn from the atmosphere.
Grasslands hold 40 percent of the predicted global arbuscular biomass, while large-scale agricultural areas show densities about 50 percent lower. Just 5 percent of fungal biodiversity hot spots fall within protected zones.
Toby Kiers, executive director of the Society for the Protection of Underground Networks and coauthor of the paper, said the maps allow scientists to identify where the fungi are concentrated and where they face threats. Ecologist Smriti Pehim Limbu noted that protecting these networks could help capture more carbon dioxide in soils.