Scientists on a quest to map the global network of fungi beneath our feet


  • Interconnected bodies of fungi form vast underground networks throughout Earth’s soils, transporting nutrients and water through ecosystems and sequestering large amounts of carbon out of the atmosphere.
  • Experts agree that protecting fungi and focusing conservation efforts underground could help mitigate global challenges such as climate change, biodiversity loss, land use change and pollution.
  • A new initiative launches in the world’s first effort to document and map network-forming fungi around the world, using eDNA and machine learning to identify and protect global hotspots of fungal biodiversity.
  • Fungi are increasingly seen as a nature-based solution to manage global carbon budgets, restore degraded ecosystems, clean up contaminated soils and accelerate the transition to sustainable agriculture.

Fungi make up about half of the living organisms in our soils, but we tend to only notice them when a toadstool or poisonous fungus appears and catches our eye. Meanwhile, scientists estimate that just underfoot, trillions of miles of fungal networks permeate the soil, carrying water and nutrients through the planet’s ecosystems and pulling carbon underground.

Today, a team of specialists is embarking on the world’s first effort to map these fungi forming underground networks by creating a global database on their whereabouts. The project, led by the Society for the Protection of Underground Networks (SPUN) and including researchers from Canada, Europe and the United States, aims to identify hotspots of underground biodiversity around the world.

“The maps will allow us for the first time to integrate information about fungal biodiversity into our conservation planning and decision making,” Colin Averill, senior scientist at ETH Zürich in Switzerland and co- founder of SPUN.

As we risk overstepping Earth’s nine planetary boundaries, the environmental limits within which current life-support systems operate, experts agree that focusing conservation efforts underground could prove vital to address global challenges such as climate change, loss of biodiversity, land use change and pollution of the biosphere.

In addition to changing land management practices to protect fungi, environmentalists are increasingly incorporating fungi into nature-based solutions to restore degraded ecosystems, clean up contaminated soils, and accelerate the transition to sustainable agriculture.

“Understanding underground fungal networks is critical to our efforts to protect the soil, on which life depends, before it is too late,” Jane Goodall, renowned environmentalist and project advisor, said in a statement. declaration.

A high resolution image of a fungal mycelium network. Image by Victor Caldas

Fungal biodiversity hotspots

The researchers first rely on the Global Mushrooms database, which contains thousands of fungal records from around the world, to create fungal distribution models using machine learning and the latest environmental measurements. They will then use the models to predict fungal diversity in parts of the world that have yet to be studied.

From April 2022, the team plans to carry out its first field collections in the Patagonian highlands and will spend 18 months collecting more than 10,000 soil samples from different habitats around the world. They will then use environmental DNA sequencing to find out which species are found in which location. Researchers will focus on potential hotspots of fungal diversity, including the Canadian tundra, the Mexican plateau, the Negev Desert in the Middle East, the prairies and high plains of Tibet, and the Russian taiga.

Mushrooms growing along a tree branch. Image by jggrz Going through Pixabay

Networks play a crucial role in the ecosystem

Mushrooms and toads are only a small component of fungi, equivalent to the flowers or fruits of plants. The main part of a fungus is its root system, known as the mycelium, which includes web-shaped threads called hyphae that extend into soils and other moist environments, such as tree trunks. rotting, in search of nutrients.

The most notable underground fungal networks are created by mycorrhizal fungi, a type of fungi that live in symbiosis with the roots of plants. Their mycelia form large, interconnected networks that take up water, nitrogen, phosphorus, and other nutrients from the soil and transmit them to plants. In return, the plants provide sugars to the mycorrhizal fungi in a process that sequesters carbon from the atmosphere in the bodies of the fungi.

The SPUN team is focused on documenting hotspots of mycorrhizal biodiversity, in part due to their enormous role in carbon storage: ecosystems with thriving underground fungal networks have been shown to store eight times more carbon than ecosystems without them. In addition, mycorrhizal networks form “super highways” for important soil microbes and have even been shown to facilitate “communication” between trees.

Still, experts say decomposing fungi shouldn’t be overlooked due to their crucial role in recycling nutrients that would otherwise remain locked up and unavailable to plants. In the process of decomposing dead organisms, decomposers emit carbon dioxide, so keeping track of their influence on the global carbon cycle is essential.

Lynne Boddy, a fungal ecologist at Cardiff University in the UK, who is not involved in the new mapping project, said that while the initiative is a welcome move to learn more about fungal networks and stressing the importance of underground biodiversity, it is not clear how the scientists plan to map fungal networks on such a huge scale.

It is estimated that there are between 2 and 5 million species of fungi in the world, of which only a fraction has been classified so far, and the size of individual fungi ranges from tiny yeasts to huge mycelia that cover several hectares; the largest mushroom ever recorded, a Armillaria gallica found in Michigan and nicknamed the “gigantic mushroom”, weighed more than a blue whale.

“There are fungal networks at many different levels and at all kinds of scales,” said Boddy, “and the decomposers are surely as important as the mycorrhizal fungi… they all have networks, it’s just that the Mycorrhizal fungi connect plants, and decomposers connect dead stuff.

Boddy also said that eDNA sequencing data does not always lead to better knowledge about species function. “We have to be very careful about how we interpret the species lists,” Boddy said. “Just because a species is there doesn’t mean it’s necessarily important in the community; we just know he’s there. Maximizing ecological knowledge through collaboration with local experts, she said, will likely be key.

SPUN’s Averill agrees. “What we need is a distributed network of scientists from around the world who live and work in these places and know them best,” he said, adding that SPUN was planning to roll out a program. ” explorer “to cultivate expertise and partner with local communities and conservation initiatives to collect data and protect habitats.

Honey mushroom
A honey fungus (Armillaria sp.). The largest individual mushroom ever recorded belonged to this genus, it weighed more than a blue whale. Image by Sinousxl Going through Pixabay

Restore fungi to restore ecosystems

One of the biggest questions SPUN researchers try to answer is how fungi are affected by global threats, including the expansion of industrial agriculture, deforestation, pollution, drought and climate change. .

Although conservationists have recorded gradual changes in the distribution of tree and plant species, it remains unclear whether underground fungal networks shifted at the same time.

“The mycorrhizal fungi mosaic is fundamentally changing and shifting,” Averill said. “It’s driven by the climate, nitrogen pollution and other factors. The thing we really don’t know on a large scale is that when these trees move, do they bring their mushrooms with them or are they left behind? “

Deforestation is “wiping out” the fungi from the soil, Averill said, “and when we plow the soils we are just tearing the soil with knives and shredding the hyphal networks, the actual bodies of the fungi. Soil organisms are further damaged when farmers treat crops with chemical fertilizers rich in nitrogen, phosphorus and potassium, which break the symbiosis between mycorrhizal fungi and plant roots. Research has also shown that precipitation contaminated with sulfur dioxide, nitrogen oxides and other air pollutants inhibits mycorrhizal relationships in forests.

Restoring the symbiotic relationship between mycorrhizal fungi and plant and tree roots could go a long way, according to Averill, in restoring degraded ecosystems and moving away from chemical inputs on farms and other managed landscapes. For example, this can be achieved in agriculture by changing practices towards no-till agriculture.

Active restoration of mycorrhizal symbiosis in plantations and reforestation projects by transplanting soil also improves tree growth and restores natural carbon storage mechanisms both above and below ground.

“There is an opportunity to integrate fungal restoration and soil microbiome restoration into our concept of ecosystem restoration and forest restoration,” Averill said, “and in the process we could build forests and ecosystems. more resilient, richer in biodiversity and more productive. “

Banner image: Mushrooms emerging from dead wood covered with moss. Image by adege Going through Pixabay

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Agriculture, Biodiversity, Biodiversity crisis, Biodiversity hotspots, Carbon sequestration, Climate change, Climate change and biodiversity, Climate change and conservation, Climate change and extinction, Conservation, Conservation solutions, Deforestation, Ecosystem engineers, Restoration of ecosystems, Ecosystems, Forgotten species, Green, Nature-based climate solutions, Plants, Research, Soil carbon

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