Under UK soils, a vast network of subterranean fungi is quietly working behind the scenes to sustain plant life and regulate the global climate. A groundbreaking new study reveals these arbuscular mycorrhizal fungi have been forming for approximately 475 million years, establishing crucial partnerships with over 70% of plants worldwide.
The fungal networks, composed of tubular cells called hyphae, stretch an estimated 110 quadrillion kilometres – a distance equivalent to nearly 750 million Earth-to-sun journeys. They supply plants with vital nutrients and water in exchange for carbon produced by the plants, drawing carbon into soils and playing a key role in regulating the climate.
Despite their profound importance, the global distribution and density of these networks were previously unknown. The study, published in Science, utilised machine-learning models and data from over 16,000 soil samples collected worldwide to produce an unprecedented global map. Dr. Justin Stewart, lead author, highlighted that a single teaspoon of soil could contain up to 10 metres of mycorrhizal network.
The research also uncovered significant threats to these vital networks, with densities in cultivated croplands averaging 47.3% lower than in natural wild ecosystems. Practices like tilling and the use of certain fertilisers and fungicides can severely impair the symbiotic relationship between plants and fungi, compromising soil's ability to store carbon and distribute essential nutrients.
Dr. Toby Kiers, a co-author, stressed that understanding these fungal systems is crucial for mitigating climate change and protecting waterways from pollution. The study aims to equip scientists and policymakers with data to identify areas where networks are thriving and at risk, set to be presented to governments at the upcoming desertification Cop in Mongolia.
Grasslands were found to possess the densest hyphal systems, with regions such as the Sudd flooded grasslands in South Sudan and various prairie and steppe ecosystems globally showing exceptionally high densities. However, these areas are frequently poorly protected and experiencing increasing degradation, highlighting the need for greater collaboration between farmers and fungi.
Supporting soil fungi could naturally enhance nutrient uptake in plants, reducing reliance on artificial fertilisers – a recommendation echoed by the researchers as they advocate for greater understanding and protection of these vital networks.