Key facts
- Global arbuscular mycorrhizal fungal networks measure an estimated 110 quadrillion kilometers.
- These networks sequester approximately 1 billion tons of carbon annually.
- Fungal networks are densest in grasslands, which are being converted to farmland.
- The study combined literature review, soil samples, machine learning, and laboratory testing.
Threads of underground fungal networks, known as arbuscular mycorrhizal fungi, are estimated to span 110 quadrillion kilometers globally, a length that could extend beyond the Solar System if laid end-to-end. This finding comes from new research published in Science, led by the Society for the Protection of Underground Networks (SPUN).
These fungal communities form vital symbiotic relationships with approximately 80 percent of plant species, providing them with essential nutrients like phosphorus and nitrogen in exchange for carbon. The networks sequester about 1 billion tons of carbon annually, preventing it from entering the atmosphere and contributing to warming. The new study utilized a combination of literature review, global soil samples, machine learning, and laboratory testing to map the distribution and density of these networks.
Researchers found that fungal network densities in croplands are roughly half that of wild ecosystems. Grasslands, which harbor about 40 percent of the world's arbuscular mycorrhizal biomass, are particularly vulnerable as they are converted to farmland at a significantly higher rate than forests. This conversion poses a threat to the ecological benefits these networks provide, including plant health and carbon storage.
The study's lead author, Justin Stewart, described the research as creating the first comprehensive map of these underground systems, providing a foundational understanding of their structure and importance. Researchers plan to present their findings to policymakers at the upcoming United Nations Climate Change Conference (COP31) to highlight the role of these networks in ecosystem protection and carbon sequestration.