WASHINGTON, United States (AFP) — Beneath the surface of forests, grasslands and farms across the world, vast fungal webs form underground trading systems to exchange nutrients with plant roots, acting as critical climate regulators as they draw down 13 billion tons of carbon annually.

Yet until recently, these “mycorrhizal networks” were greatly underestimated: seen as merely helpful companions to plants rather than one of Earth’s vital circulatory systems.

American evolutionary biologist Toby Kiers has now been awarded the Tyler Prize for Environmental Achievement — sometimes called the “Nobel for the environment” — for her work bringing this underground world into focus.

By charting the global distribution of mycorrhizal fungi in a worldwide Underground Atlas launched last year, Kiers and her colleagues have helped illuminate below-ground biodiversity — insights that can guide conservation efforts to protect these vast carbon stores.

Plants send their excess carbon below ground where mycorrhizal fungi draw down 13.12 billion tons of carbon dioxide — around a third of total emissions from fossil fuels.

“I just think about all the ways that soil is used in a negative way -- you know, terms like ‘dirtbag,’” the 49-year-old university research chair at Vrije Universiteit Amsterdam told AFP in an interview. “Whereas a bag of dirt contains a galaxy!”