Underground “Wood Wide Web” Could Reshape Climate Science—and Agriculture—Here’s What’s Next
Scientists have mapped the world’s hidden fungal network for the first time, revealing a carbon-storing system so vast it would stretch 10% of the Milky Way if laid end-to-end—and its future hinges on how we treat grasslands and farms. According to a landmark study in Science, arbuscular mycorrhizal fungi (AMF) form a global web of hyphae that spans 68 quadrillion miles, with wild grasslands hosting the densest concentrations. But agricultural practices are slashing these networks by up to 50%, threatening soil health and carbon storage at a time when both are critical to climate goals.
This isn’t just about soil—it’s about rewriting how we think about ecosystems, food security, and even drought resilience. Here’s what the data tells us about where this research is headed, and why it could force a reckoning in conservation and farming.
—
### Why This Fungal Network Matters More Than You Think
The AMF network isn’t just a passive part of soil—it’s an active partner in plant survival. These fungi trade carbon from plants for nitrogen and phosphorus, a relationship so vital that 4.3 billion tons of CO₂ equivalent are absorbed annually by AMF, roughly 11% of global fossil fuel emissions in 2021, according to the study’s lead author, Justin Stewart, an evolutionary biologist at the Society for the Protection of Underground Networks (SPUN).
Yet until now, scientists lacked a global map of where these networks thrive—or vanish. The new study, which analyzed 16,669 soil cores from 322 studies across nine biomes, found:
- Wild grasslands (like the Everglades) contain 40% of the world’s fungal biomass in the top 6 inches of soil—making them a far more efficient carbon sink than forests.
- Croplands have 50% lower hyphal density, likely due to fungicides and synthetic fertilizers that disrupt the fungi-plant symbiosis.
- If all hyphae were laid in a straight line, they’d stretch 68 quadrillion miles—nearly a billion times the Earth-sun distance.
Why it matters: These fungi aren’t just storing carbon—they’re also boosting plant drought resistance and suppressing soil-borne diseases, according to Edouard Evangelisti, a plant scientist at Côte d’Azur University. “The abundance of living hyphae is important, but we also need to know how quickly they grow, die, and lock carbon into soil,” he told Live Science. “This map is the first step in answering those questions.”
—
### The Coming Collapse of Grasslands—and What It Means for Food
Grasslands cover 20% of Earth’s land surface, yet they’re disappearing at an alarming rate. The United Nations estimates that 50% of the world’s grasslands have been lost since the 1950s, converted to farmland or urban sprawl. The new study underscores why this loss isn’t just an ecological tragedy—it’s a carbon accounting disaster.
Take the Great Plains of the U.S., where 30% of native prairie has been plowed under since the 1930s. A 2022 study in Nature Sustainability found that restored prairie soils sequester 30% more carbon per acre than cornfields. Yet today, only 4% of original tallgrass prairie remains—and with it, much of the AMF network that once thrived there.
What happens next: As grasslands vanish, so does the fungal infrastructure that keeps them resilient. “These are areas people are ripping up because it’s easier to plow grass than trees,” Stewart said. “But we’re losing a hidden carbon bank in the process.”
Key question: If grasslands are more efficient carbon sinks than forests, should climate policies prioritize their protection over tree-planting efforts? Some scientists argue yes—especially in regions like the Pampas of Argentina or the steppes of Mongolia, where fungal-rich grasslands are still intact.
—
### Agriculture’s Hidden Fungicide Problem—and How Farmers Could Fix It
The study’s most striking finding? Fungicides and synthetic fertilizers are decimating AMF networks in croplands. While the exact agricultural practices responsible weren’t pinpointed, the data suggests a clear pattern: where nitrogen and phosphorus fertilizers dominate, fungal density plummets.
Consider Indonesia’s palm oil plantations, where fungal biomass in soil dropped by 60% after conversion from rainforest to farmland, according to a 2023 study in Global Change Biology. The culprit? Heavy fungicide use and soil disruption from machinery.
But there’s hope: Regenerative agriculture—techniques like cover cropping, reduced tillage, and organic fertilizers—has shown promise in reviving AMF networks. A 2024 trial in Iowa found that farms using no-till methods and compost saw hyphal density rebound by 40% within three years.
Pro tip for farmers: If you’re looking to boost soil health, planting clover or alfalfa as cover crops can attract AMF, according to Andrea Genre, a fungal expert at the University of Turin. “These plants are natural fungal magnets,” she said. “They don’t just feed the soil—they rebuild the underground web.”
—
### The Next 5 Years: How This Research Will Change Policy and Science
The global AMF map is just the beginning. Researchers are already racing to fill gaps—particularly in tropical rainforests and deserts, where data is sparse. Stewart predicts major updates to the map within five years, with new insights into:
- Drought resilience: AMF networks may help plants survive water scarcity by expanding their root systems. A 2023 study in Science Advances found that wheat crops with active AMF networks used 20% less water during droughts.
- Climate modeling: Current carbon models ignore AMF entirely. If incorporated, they could shift global carbon budgets by 5–10%, according to NASA’s Carbon Monitoring System.
- Policy shifts: The EU’s Farm to Fork Strategy already aims to reduce synthetic fertilizers by 50% by 2030. The AMF data could accelerate this goal by proving that fungal-friendly farming boosts yields while cutting emissions.
Did you know? Some countries are already acting. Costa Rica’s “Payment for Ecosystem Services” program now includes soil fungal health as a metric for land stewards, paying farmers to preserve native grasslands and reduce fungicide use.
—
### FAQ: Your Biggest Questions About the Underground Fungal Network
1. How do fungi actually “talk” to plants?
They don’t talk—they trade nutrients via chemical signals. Plants release sugars (carbon) into the soil, and fungi respond by releasing phosphorus and nitrogen through their hyphae. Some evidence suggests they may also warn plants of pests via volatile organic compounds, though this is still debated.
2. Can I grow AMF in my garden?
Yes! Many nurseries sell AMF inoculants (like Glomus species) for home gardens. Mix them into soil when planting, and pair them with clover, beans, or tomatoes, which thrive with fungal partners. Avoid chemical fungicides—they’ll kill the fungi.
3. Are there regions where AMF are already protected?
Yes, but they’re rare. Yellowstone National Park’s grasslands and Australia’s Kimberley region have strict limits on fungicide use and prioritize native plant restoration to preserve AMF. Conservation groups like SPUN are pushing for similar protections globally.
4. Will this research change how we grow food?
Likely. The data supports a shift toward regenerative farming, where fungal health is monitored alongside soil pH and water retention. Companies like Indigo Ag already sell AMF-enhanced seeds, and some European dairy farms are seeing 20% higher milk yields by boosting fungal networks.
5. How can I help protect AMF?
- Support grassland conservation (donate to groups like The Nature Conservancy).
- Choose organic or regenerative-labeled food when possible.
- Plant native grasses and clovers in your yard.
- Advocate for policies that reduce fungicide use (e.g., PANNA’s global fungicide campaign).
—
### The Bottom Line: A Hidden World on the Brink of Change
The AMF network is Earth’s invisible circulatory system—one that’s being disrupted faster than we’re mapping it. The next decade will determine whether we treat it as a liability to be cleared for farms or a lifeline to be preserved.
One thing is clear: the most efficient carbon sinks on Earth may not be forests, but the grasslands we’re paving over. And the fungi beneath them? They’re not just holding soil together—they’re holding our climate strategy together too.
What’s your take? Should governments prioritize grassland protection over tree-planting? Or is there a middle ground? Share your thoughts in the comments—or dive deeper with our guides on [regenerative agriculture](link-to-internal-article) and [soil carbon science](link-to-internal-article).
Want more stories like this? Subscribe to our Soil & Climate Science newsletter for cutting-edge research delivered straight to your inbox.
Related reading
