Vast networks of underground microscopic fungi play a crucial role in Earth’s ecosystems, and there is a lot we don’t know about them.
More than a quarter of Earth’s species live in underground soils, including webs of fungi that help store large amounts of carbon, provide most plants with most of the nutrients they need to survive, and allow plants to plants receive important signals from others.
Now, a team of scientists is launching a one-of-a-kind effort to map the world’s mycorrhizal fungi, a process they hope can identify fungal biodiversity for conservation, increase understanding of how these species interact within ecosystems, and sustain more. carbon in the soil. .
“These fungal webs have been a global blind spot on the conservation and climate agendas. People have not woken up and realized that there is this ancient form of life support under our feet, ”said Toby Kiers, evolutionary biologist and professor at the Vrije Universiteit Amsterdam, who co-founded SPUN, the Society for the Protection of Underground Networks.
“We need to know where the biodiversity hotspots are. Where are the underground Amazon forests? “Kiers said.
Most of these mushrooms are found underground and are too small to see without a microscope, but they are abundant. A handful of soil contains nets of tubular mushrooms that would stretch 60 miles if spread out, Kiers said.
Gardeners may recognize mycorrhizal fungi, which are pronounced my-core-eye-zal, like the white filaments that extend from the roots of trees and other plants, attached to clods of earth as old, fibrous hair. Combined in layers, they are massive networks of fungal threads called mycelium.
Kiers described the tangles of mycorrhizal fungi as a “continuous pipe system” that branches, fuses and flows with nutrients such as nitrogen and phosphorus.
“We follow them like a river,” Kiers said, adding that nutrients can flow in more than one direction.
Networks, which generally share a mutually beneficial relationship with the plants to which they connect, are critical to the functioning of forests and other ecosystems.
“Fungi massively extend the root systems of trees,” said Colin Averill, co-founder of SPUN and senior scientist at ETH Zürich. Some help break down dead plants and animals and recycle nutrients.
The way scientists talk about creatures can seem like fables.
Without the mycorrhizal fungi, the plants may never have reached the ground. Hundreds of millions of years ago, all flora was aquatic until an association with mycorrhizal fungi allowed them to settle on land, Kiers said.
Plants can receive chemical signals through networks, helping them share resources, learn from neighbors about pests and receive warnings about competitors, recent studies suggest. The pioneering work of Canadian scientist Suzanne Simard and others has changed the idea that trees are lone competitors vying for space, water and sunlight in the forest.
Instead, through fungal networks, “the trees may really be cooperating as a family unit,” Averill said. More research is needed to better understand the nature of relationships.
SPUN aims to map the world’s fungal networks using machine learning to identify where biodiversity hotspots may exist, and then work with local scientists to collect samples in remote locations where they have never been collected before.
The DNA of each species of fungus within the sample will be extracted, sequenced, and then mapped to its location, giving scientists a census of which species live and where. The scientists plan to combine the information with data on the surrounding climate and vegetation cover to better understand patterns in different ecosystems.
The nonprofit, which recently received a $ 3.5 million donation from the Jeremy and Hannelore Grantham Environmental Trust, expects to collect 10,000 soil samples over the next 18 months.
It’s work that couldn’t have been done without recent advances in genomic sequencing, which allow scientists to see the genetic makeup of these tiny species.
“We really didn’t have the tools to look at the diversity and the types of organisms that live underground,” Averill said. “Now it feels like we’re on the ground.”
Microorganisms, including bacteria and fungi, play a critical role in the carbon cycle, and the ability to quickly analyze what lives within soils offers a deeper understanding of our changing climate and possible solutions.
“It really is a frontier,” said Serita Frey, a microbiologist and professor at the University of New Hampshire who is not involved in the project. “That cannot be an exaggeration. There are so many things that we still don’t know about what goes on underground. “
Frey said the mapping project could help complete scientists’ understanding of microbial communities and help identify areas that deserve conservation.
“This type of mapping has been done for macro-organisms for a long time. The idea of mapping microorganisms is quite new and just something that we have been able to do in the last five to eight years, ”said Frey.
As the world warms, understanding how mycorrhizal fungi and other microorganisms interact with the soil could be crucial in slowing warming and adapting to a new climate.
“We are beginning to understand this huge role that microbes play in the global carbon cycle, which has important implications for the climate and future climate,” Frey said. “The way these microbes are managed will be really important.”
Fungi promote plant growth, which sequester carbon in trees and other plant species. They also help bury and store carbon in the soil.
About 75 percent of Earth’s carbon is in the soil, and scientists want to keep it there while preserving these biodiversity hotspots.
“We have this incredible carbon sink,” Kiers said. “We can’t lose it.”
They are also exploring which adjustments to the system could promote greater carbon sequestration or reduce fertilizer use in agriculture, which may have environmental costs.
“There is a three-fold variation in how fast a tree grows, depending on which fungi live in those soils,” Averill said. “Can we accelerate carbon sequestration in forests by manipulating which mycorrhizal fungi live on the forest floor?”