We’re trying to make people aware of just how ubiquitous and important they are so that we can better protect them.
“I remember clearing out plant root systems and seeing these mycorrhizal fungi actually penetrate into the plant cell and make these beautiful structures inside that look like mini trees, with a single trunk and many tubes as branches."
Toby Kiers, an evolutionary biologist, recalls her first forays into the world of mycorrhizal fungi while working in Panama in the late 1990s. "From there, I was hooked.
“The conventional wisdom was that these were pathogenic fungi. It was so dramatic that they were actually penetrating the cell – they looked like a parasite,” she says.
Transformative
Scientific thinking has changed radically since then, with mycorrhizal fungi now recognised as an essential part of the Earth’s circulatory system, forming vast underground trading networks that exchange nutrients with plant roots across forest floors and agricultural lands.
This shift owes much to Kiers’ work at Vrije Universiteit Amsterdam, where she is now research chair. This year began with her being awarded the Tyler Prize for Environmental Achievement, granted annually since 1974, previous recipients including Jane Goodall, Michael Mann and Gretchen Daily.
The award recognises her “transformative research” on the role of mycorrhizal fungi in underground carbon flows, biodiversity and climate resilience.
Kiers and her colleagues combine ecological science with cutting-edge technologies including high-resolution imaging, DNA sequencing and global mapping.
Their studies have revealed that fungi ‘trade’ nitrogen and phosphorus with plants, in return receiving around 13 billion tonnes of carbon every year – roughly equivalent to one-third of global fossil fuel emissions.
Advocates
However, Kiers’ research has also identified that 90 per cent of the world’s most diverse underground fungal systems are unprotected and largely absent from existing conservation frameworks.
In recognition of this, in 2021 Kiers co-founded the Society for the Protection of Underground Networks (SPUN), a global initiative working to map mycorrhizal biodiversity and advocate for their protection.
SPUN has produced a high-resolution digital Underground Atlas that predicts the global distribution of underground mycorrhizal fungi. The tool allows decision makers to identify where highly diverse and threatened fungal systems require protection.
SPUN has also partnered with New York University Law’s More-than-Human Life (MOTH) Program to equip scientists with legal and policy skills to help document and protect mycorrhizal fungi in biodiversity hotspots around the world.
We’re trying to make people aware of just how ubiquitous and important they are so that we can better protect them.
Launched earlier this year, the ‘Underground Advocates’ initiative helps local scientists and communities channel their findings into legal and policy processes so that fungal biodiversity is incorporated into climate agendas and conservation legislation.
Ubiquitous
The programme uses what Kiers describes as a “decentralised science” approach, where the information comes from the bottom up rather than following an agenda imposed top-down.
“All the progress that we’ve made in understanding these organisms is because we’re working with scientists all over the world who are mapping mycorrhizal fungi in their home ecosystems and asking different questions than we would ask,” she says.
“One of the big pulls right now is for people to realise that these fungi lie at the base of resilient ecosystems – and even agricultural systems – because they act like a pump,” she adds, referring to the exchange of nutrients between plants and fungi.
Mycorrhizal fungi can also increase plants’ tolerance to heavy metals and improve water uptake. They even make flowers bigger and sweeter, which supports pollinator populations.
Mycorrhizal fungi acted as the root system for plants for tens of millions of years before plants evolved their own roots, Kiers says. “We’re trying to make people aware of just how ubiquitous and important they are so that we can better protect them,” she adds.
Restoration
Kiers is excited about the potential to boost protection of fungi as technological advances bring forward new data at the same time as awareness of mycorrhizal networks grows.
For example, her team can analyse DNA sequencing from soil samples collected by SPUN partners using machine-learning models to build predictive maps of organisms too small to be seen with the human eye.
“It’s a perfect storm. This data is now becoming available, and the more it becomes available, the more that decision makers see the importance of these networks and fungi in general,” she says.
Kiers and her team have also heard from many scientists and conservationists working on restoration projects that their work is not progressing as well as they had hoped – and mycorrhizae could be the missing key.
“There’s convincing data that native mycorrhizal fungi can boost restoration success. People know that when they restore, they should use native plants.
System
But now they’re starting to realise that you need to restore those native plants with their native fungi,” she says. SPUN is now working with restoration managers to develop toolkits showing how native mycorrhizal strains can be used.
Yet as awareness grows of the critical role fungi could play in helping the world deal with climate breakdown, the threats to them are also increasing. Land-use change through deforestation and urbanisation are among the biggest pressures, according to Kiers.
Use of fungicides and fertilisers in agriculture is another major problem. When plants have access to nutrients such as nitrogen and phosphorus from elsewhere, they reduce the carbon they provide to fungal partners.
“That’s a big worry, because then the whole system falls apart,” Kiers says. “These fungi form a physical scaffold in the ground that holds the soil together and keeps it from eroding. If we lose that, then soil will wash away.”
Diverse
Protecting mycorrhizal fungi can take many forms and is very specific to circumstances. Some grassland fungi, for example, can be lost through low levels of grazing, and others through high levels, so management strategies need to be tailored to specific fungi.
“For mycorrhizal fungi in particular, the most import-ant thing is to protect the native plants above ground. We want to make sure that the productivity above ground is at its optimal so that they can keep feeding the networks below ground,” Kiers says.
Studying mycorrhizal networks has also changed the way she sees the world above ground. The partnership between plants and fungi evolved around 450 million years ago, she notes.
“It was fungi that first helped aquatic plants colonise land and led to all of the diverse ecosystems that we have above ground, from rainforests to deserts to wetlands.
Nodes
"A very extreme way of thinking about it is that the fungi are actually growing the plants in order to capture carbon. It’s quite interesting to see the world like that because you start to appreciate what’s happening below ground.”
She adds: “Most people write off soil, but it’s actually where all the mysteries lie. How does it lead to this riot of chaos above ground? I think that is one of the biggest questions going into 2026.”
Scientific research into mycorrhizal networks has accelerated rapidly in recent years. Since Kiers gave a TED talk in 2019 about lessons fungi could teach humans about markets and economics, she has worked with other researchers at Vrije Universiteit Amsterdam and the biophysics institute AMOLF to develop imaging robots capable of producing high-resolution maps of mycorrhizal networks.
“In 2019 we could just see that there were active flows, and now we can map both the road system and the flows as if it’s a Google Maps for fungi. We can track half a million nodes simultaneously across these experiments to see how fungi navigate space, and how they build supply chains.”
Solutions
There is much humans could learn from the trading rules of fungi, Kiers believes. Their networks have been optimised by natural selection for hundreds of millions of years, so studying what drives the plant–fungi partnerships to break apart, what the optimal size of trading partners is, and how small local markets evolve could offer valuable insights.
“We can watch these trade strategies evolve and study tipping points for when and how relationships form or break down. The most interesting thing for me is really trying to understand the inner lives of fungi themselves, because I think they’ve evolved a much more complicated system of trade than humans have,” she says.
Fungi’s time has finally come, Kiers believes. “Fungi really allow us to reimagine the world, and offer totally new ways of tackling the biodiversity and climate crisis.
“We’re missing key biodiversity hotspots by only focusing on what’s above ground. Fungi offer a library of solutions for so many problems that we’re facing. More and more people are starting to understand that, so we need to move fast to protect them,” she says.
This Author
Catherine Early is the chief reporter for The Ecologist and a freelance writer and editor specialising in the environment and sustainability.
You can read more about Toby Kiers’ work at www.tobykiers.com and find out more about SPUN at www.spun.earth.
