Soil Fungi: Earth's Climate Regulators Revealed in Global Map

The world's soils harbor an immense, largely unseen infrastructure of arbuscular mycorrhizal fungi, vital for sustaining plant life and regulating climate. A new global mapping effort, utilizing machine-learning models and extensive soil core data, has quantified the scale of these hyphal networks. Researchers calculated that if laid end-to-end, these fungal systems would stretch an astounding 110 quadrillion kilometers, equivalent to nearly 750 million journeys from Earth to the sun.

These subterranean networks form critical partnerships with over 70% of plant species, facilitating nutrient and water exchange while drawing carbon into the soil. Despite their ecological significance, their distribution remained poorly understood until this study. The research also identified significant threats, noting that cropland soils, on average, exhibit 47.3% lower fungal network densities compared to wild ecosystems. Practices such as tilling and the application of fertilizers and fungicides are identified as major disruptors.

The degradation of these fungal networks has far-reaching consequences. Reduced network density impairs the soil's capacity for carbon sequestration and nutrient distribution, and diminishes their protective role for waterways against chemical pollutants. The study aims to equip scientists and policymakers with data to identify thriving and threatened fungal systems, with findings set to be presented at the upcoming desertification COP in Mongolia.

Grasslands, particularly regions like the Everglades and South Sudan's Sudd, were found to have the densest hyphal systems. The researchers advocate for greater collaboration between agriculture and fungi, suggesting that supporting soil fungi could naturally enhance crop yields and soil carbon storage, thereby reducing reliance on artificial fertilizers and aiding efforts to address food security and climate change.