Vast arrays of microscopic subterranean fungi play a crucial role in Earth’s ecosystems – and we don’t know much about them.
More than a quarter of terrestrial species live in underground soils, including fungal networks that help store huge amounts of carbon, provide most plants with the majority of the nutrients they need to survive and enable plants to survive. to receive important signals from others.
Today, a team of scientists is launching a one-of-a-kind effort to map mycorrhizal fungi around the world, a process they hope can identify fungal biodiversity for conservation, better understand how these species interact within ecosystems, and keep more carbon in the soil.
“These fungal networks have been a global blind spot in conservation and climate programs. People didn’t wake up and realize that there was this ancient form of life support under our feet, â€said Toby Kiers, evolutionary biologist and professor at 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 Amazonian forests in the basement? Kiers said.
Most of these fungi are underground and too small to see without a microscope, but there are many. A handful of soil contains tubular mushroom networks that would stretch for 60 miles if extended, Kiers said.
Gardeners might recognize mycorrhizal fungi – pronounced my-core-eye-zal – as the white filaments that extend from the roots of trees and other plants, clinging to clods of earth like stringy, old hair. Combined in layers, they are massive networks of fungal threads called mycelia.
Kiers described mycorrhizal fungal tangles as a “continuous pipe system” that branches, merges, and flows with nutrients like nitrogen and phosphorus.
“We follow them like it’s a river,†Kiers said, adding that nutrients can flow in multiple directions.
Networks, which generally share a mutually beneficial relationship with the plants to which they connect, are essential for 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 Zurich. Some help break down dead plants and animals and recycle nutrients.
The way scientists talk about creatures may sound like fables.
Without mycorrhizal fungi, plants might never have reached dry land. Hundreds of millions of years ago, all flora was aquatic until a partnership with mycorrhizal fungi allowed them to take root on earth, Kiers said.
Plants can receive chemical signals through networks, which helps 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 overturned the idea that trees are solitary competitors competing for space, water and sunlight in the forest.
Instead, through fungal networks, “trees can really cooperate 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 biodiversity hotspots, 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 in the sample will be extracted, sequenced and then mapped to its location, giving scientists a census of the species living where. 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, hopes to collect 10,000 soil samples over the next 18 months.
This is work that could not 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 see the diversity and types of organisms living underground,†Averill said. “Now we feel like we’re in the ground. “
Microorganisms, including bacteria and fungi, play a vital role in the carbon cycle, and the ability to quickly analyze what lives in soils provides a better understanding of our changing climate and possible solutions.
“It really is a border,†said Serita Frey, a microbiologist and professor at the University of New Hampshire who is not involved in the project. “It can’t really be overstated. There is so much that we do not yet know about what is going on underground.
Frey said the mapping project could help scientists better understand microbial communities and help target areas worth conserving.
“This type of mapping has long been done for macroorganisms. The idea of ​​mapping microorganisms is pretty new and it’s just something we’ve been able to do over the past five to eight years, â€Frey said.
As the world warms, understanding how mycorrhizal fungi and other microorganisms interact with the soil could be crucial in slowing the warming and adapting to a new climate.
“We have just understood this disproportionate role microbes play in the global carbon cycle, which has important implications for the climate and the future climate,” Frey said. “How these microbes are managed is going to be very important. “
Fungi promote the growth of plants, which sequester carbon in trees and other plant species. They also help bury and store carbon in the soil.
About 75 percent of terrestrial carbon is in the soil, and scientists want to keep it there by preserving these biodiversity hotspots.
“We have this incredible carbon sink,†Kiers said. “We cannot lose it.”
They are also exploring changes to the system that could promote greater carbon uptake or reduce the use of fertilizers in agriculture, which can have environmental costs.
“There is a threefold variation in the speed of a tree’s growth, depending on the fungi that live in those soils,†Averill said. “Can we accelerate carbon capture in forests by manipulating which mycorrhizal fungi live in forest soil?” “
