Key facts
- Global topsoils contain an estimated 110 quadrillion kilometers of arbuscular mycorrhizal fungal networks.
- These fungal networks move approximately 4 billion tons of carbon dioxide equivalent into soils annually.
- Grasslands hold about 40 percent of the world's fungal network infrastructure.
- Agricultural croplands have 50% lower fungal network density compared to natural ecosystems.
- The study utilized over 16,000 soil cores and machine-learning models for mapping.
Scientists have unveiled the first comprehensive global maps of underground fungal networks, specifically arbuscular mycorrhizal fungi (AM fungi), revealing an extensive 'superhighway' beneath our feet. These networks, formed by thread-like structures called hyphae, connect with the roots of most plant species, facilitating the movement of nutrients, water, and carbon throughout ecosystems. The research, published in the journal Science, estimates that global topsoils contain approximately 110 quadrillion kilometers of these fungal networks, a distance equivalent to nearly one billion trips between the Earth and the Sun.
The study found that these underground systems play a significant role in climate regulation, soil health, biodiversity, and food production. It is estimated that the fungal networks move around 4 billion tons of carbon dioxide equivalent into soils each year, accounting for about 11 percent of annual human-related carbon emissions. However, the research also highlighted that agricultural croplands have fungal network densities that are roughly 50 percent lower than those found in natural ecosystems, potentially reducing the soil's capacity for carbon storage and nutrient recycling.
AM fungi form symbiotic relationships with nearly 70 percent of plant species, exchanging energy from photosynthesis for essential nutrients and water absorbed from the soil. Scientists refer to these systems as 'living infrastructure' due to their vital support for ecosystems. To create the global maps, researchers analyzed data from over 16,000 soil cores worldwide, employing machine-learning models and advanced robotic imaging technology to estimate the density and extent of fungal networks.
The findings indicate that grasslands, which contain about 40 percent of the world's AM fungal infrastructure, are particularly vulnerable as they are being converted to agricultural land at a much faster rate than forests and are among the least protected ecosystems. The study emphasizes the need to incorporate fungi into conservation and climate strategies. Interactive maps of this mycorrhizal infrastructure have been made publicly available to aid policymakers and conservationists.