In his 2016 book The Hidden Life Of Trees, German author and forester Peter Wohlleben writes about how fungal networks have an integral relationship with trees. Not only do they help them exchange nutrients, they help in sending warning signals if a tree is under attack from pests or other predators. It may not be a stretch to say that trees and fungal networks have a “friendship” of sorts.
While a lot is known about plants, trees and the need to conserve them, a new non-profit science initiative—the Society for the Protection of Underground Networks (SPUN)—hopes to map and preserve the world’s underground fungal life by using machine learning and collaborating with researchers worldwide. Their ultimate goal: fighting climate change. “Protecting underground ecosystems is crucial to fighting climate change. In particular, we are focused on protecting fungal networks that are a massive carbon sink, and can make up over 50% of the living biomass of soils,” says Toby Kiers, evolutionary biologist and co-founder of SPUN. A carbon sink is anything that absorbs more carbon from the atmosphere than it releases.
Unknown to us, the world beneath our feet is home to an entire ecosystem. According to a 2020 report from the Food and Agriculture Organization (State Of Knowledge Of Soil Biodiversity—Status, Challenges And Potentialities), soils are home to 25% of all species on Earth. More importantly, though, current trends suggest that by 2050, over 90% of Earth’s soil will be degraded. Fungal networks could be key in averting such a crisis.
As Kiers explains, fungal networks are the base of healthy soils. “They underpin life on earth,” she says. They can help sequester carbon, move nutrients such as phosphorus and protect ecosystem biodiversity. “Fungi create a sticky living seam that holds soil together; remove the fungi, and the ground washes away,” Kiers explains on email. “Plant roots feed carbon to these fungal networks in exchange for nutrients the fungi collect from the soil. These networks form nutrient highways between plant roots and the soil. In science, we call them ‘mycorrhizal fungi’,” she adds. Organisms such as bacteria also use these fungal “highways” to travel between different roots of a plant.
Writing in Wohlleben’s book, Canadian scientist and forest ecologist Suzanne Simard—best known for her pioneering research on such underground networks that connect our trees and the book Finding The Mother Tree: Discovering The Wisdom Of The Forest—describes “mycorrhizal fungi” as “mutualistic”, interacting with trees in a carbon-nutrients exchange. In fact, billions of tons of carbon dioxide flow annually from plants to fungal networks. This helps make soils the second largest global carbon sink, after oceans.
Kiers says it is not clear how these networks will respond to climate change. “So, we need to map them to understand how their distribution is going to change in response to climate change.... Our aim is to find and map the ‘Amazon forests’ of the underground,” she adds.
Over the next 18 months, they will work with researchers and local communities around the world to collect around 10,000 fungal DNA samples from diverse ecosystems, with a focus on underexplored regions and those facing increasing threats from land-use change. Their first expedition is to Patagonia in April.
The scale of this project—a complete map of Earth’s underground networks—is so massive that it requires global participation. As Kiers says, the SPUN team needs to engage people all over the world to collect samples and become “myconauts”—“myco” is fungus, and “naut”, explorer. “This project can only be successful if we are able to work with communities all over the world to help us sample soils around the globe. But setting up an infrastructure to process samples from all over the world is a big challenge,” she adds.
Apart from funds—in November, they received a multimillion-dollar donation from the Jeremy and Hannelore Grantham Environmental Trust—and sequencing hundreds of thousands of samples in different countries, the other challenge is timing. “Fungal networks are disappearing at an alarming rate. Networks are threatened by agricultural expansion, deforestation and urbanisation. So we need to move fast to protect them before they are gone,” Kiers explains.
Once ready, this map will also help scientists link different fungal communities to their functions and ecosystems in the future. For example, the ability to recycle nutrients or better retain carbon. Prof. David Kothamasi, a biologist and legal scholar at the University of Strathclyde, Glasgow, and the University of Delhi, says these maps could also help in documenting new fungal species—for the networks stretch to quadrillions of kilometres.
“The efforts of SPUN will allow future researchers and mathematicians to model changes in climate patterns and land use by predicting the distribution of fungal networks as they shift in response to climates and patterns of land use, in the same manner as they already do for global vegetation, climates and ocean currents,” says Prof. Kothamasi, who has been working on mycorrhizas and other soil microbial groups for 20-25 years.
The work of researchers like Wohlleben and Simard—who is also one of the science advisers for SPUN—has brought to the surface many secrets about underground fungal networks. Kiers believes there is so much more to learn about these “coral reefs of the soil”.
“As scientists, we have documented the importance of fungal networks for decades. But this work has been inaccessible,” she says. “Underground climate science is still in its infancy. But people are finally starting to take notice of its importance.”