The first global map of underground fungal networks reveals a hidden highway, 68 quadrillion miles long, that helps sustain life on Earth and store carbon in the soil.
Underneath forests, grasslands, wetlands, and even many agricultural fields, there is an extensive underground fungal network that supports plant life and plays an important role in the global carbon cycle. Scientists have now created the first global maps showing where these networks are located and how present they are across the planet.
Research published in the magazine sciencesfocuses on arbuscular mycorrhizal fungi, known as AM fungi. Alongside the study, the researchers released an interactive visualization that reveals the massive scale of this hidden biological infrastructure. The new maps are expected to help scientists and policy makers identify areas where these fungal networks thrive and where they may be at risk.
Among the main findings of the study:
- The global topsoil contains about 110 quadrillion km of arboreal mycorrhizal fungal network, which consists of microscopic tubular structures called hyphae. This distance is approximately a billion times the distance from Earth to the Sun.
- Grassland ecosystems contain an estimated 40% of the Earth’s arboreal infrastructure.
- Areas expected to have particularly dense networks include the flooded grasslands of South Sudan, the Everglades of Florida, and the Tibetan Plateau.
- AM fungal networks transfer an estimated 4 billion tons of CO2 to the soil each year (equivalent to 11% of all human-related CO2 emissions).
- Large-scale cropland is expected to have approximately 50% lower grid density on average. The researchers note that additional work is needed to understand how specific agricultural practices affect fungal health, but low mesh density may limit soils’ ability to store carbon, recycle nutrients, and withstand environmental stresses.
Mapping the Earth’s hidden fungal infrastructure
Arbuscular mycorrhizal fungi form mutually beneficial partnerships with about 70% of the plant Classify All over the world. Plants supply the carbon produced by fungi PhotosynthesisWhile fungi in return provide water and nutrients.
These underground networks act as living infrastructure that supports ecosystems and helps transfer carbon into the soil. Although researchers have previously mapped global patterns of belowground fungal biodiversity and created a digital resource called Underground Atlas To identify potential biodiversity hotspots, no study has attempted to estimate and visualize the physical density and global distribution of AM fungal networks themselves.
To build the new maps, scientists combined data from more than 16,000 soil samples collected from around the world. They then used machine learning models that incorporated environmental information from deserts, forests, tundra and other ecosystems to estimate network density in areas that had not been directly sampled.
The team also collaborated with the Behavioral Physics Group at the AMOLF Research Institute. Using automated imaging, the researchers analyzed more than 300,000 live AM fungal hyphae grown under laboratory conditions to help calibrate their models.
Based on these combined data sets, the researchers estimate that AM fungal networks extend approximately 110 quadrillion km globally and contain about 300 megatonnes of carbon (4-6 times the mass of all living humans).
Lead author Dr Justin Stewart, from the Society for the Protection of Underground Networks (SPUN), said: “It is difficult to overstate the importance and magnitude of these fungi.” “There can be up to 10 meters (32 feet) of mycorrhizal network in a teaspoon of soil.”
A hidden system that moves carbon and nutrients
Scientists often compare mycorrhizal networks to a planetary circulation system because they transport carbon, water and nutrients through underground ecosystems.
In healthy soil, these fungal networks can expand the effective reach of plant roots by up to 100 times and provide more than 80 percent of the plant’s phosphorus needs.
“With the emergence of new technologies in high-resolution imaging, machine learning and robotics, we are beginning to uncover what has long been hidden beneath our feet,” said co-lead author Dr Corentin Bisot, a biophysicist at AMOLF. “We are learning how the complex bodies of network-forming fungi transport nutrients and help regulate climate.”
To help communicate the findings, the researchers collaborated with award-winning data visualization designer Moritz Stefaner to create the model Mycorrhizal infrastructure map.
The project provides the most detailed view to date of the Earth’s innate infrastructure, with estimates calculated per kilometre2 From terrestrial terrain where sufficient data are available (except for ice caps and areas where sufficient forecast data is lacking). Basic data is also made available to the public so that governments and other decision makers can begin monitoring the health of these important secret societies.
Carbon tracking through underground networks
A number of members of the research team Previously published A nature Cover story examining how fungi and mycorrhizal plants form highly efficient biological trading networks that exchange carbon and nutrients.
This previous work measured the movement of carbon through fungal transport systems at speeds up to 120 µm/s (if one were inside the network, these speeds would be felt at about 400 km/h).
The new study expands this work by helping researchers understand how fluxes of carbon and nutrients work on a planetary scale.
Threats to fungal networks
The findings also highlight potential risks to these underground systems.
The study predicts that mycorrhizal network density in farmland is approximately half that in terrestrial ecosystems. The researchers also found that wild grasslands contain approximately 40% of the world’s arbuscular mycorrhizal biomass.
At the same time, grasslands remain among the least protected ecosystems on Earth and are in decline Converting it into agricultural land at a rate four times the rate of forests.
The results support previous research conducted by SPUN scientists that showed this 95% of biodiversity hotspots For arbuscular mycorrhizal fungi located outside protected areas.
For evolutionary biologist Dr. Toby Keres, executive director of SPUN, these findings could help improve climate policy.
“Fungi have been ignored in climate and conservation for too long. Now is the time to change that course.”
Keres was recently named a MacArthur Fellow and received the Tyler Prize, often referred to as the “Nobel Prize for the environment,” for her work in plant-fungal systems.
A vast underground world that remains largely unknown
Although the extraordinary scale of fungal networks on Earth has been revealed, researchers stress that there is still much to be discovered.
Co-author and biologist Dr Merlin Sheldrake added: “Mycorrhizal fungi have shaped life on Earth for hundreds of millions of years, but we still understand very little about how the infrastructure for these living transport systems is distributed across the planet.” “This study is an exciting step toward understanding how the planetary circulation system works, and suggests ways we can better work with fungi to help address many of the unfolding challenges of our time, from food security to climate change.”
The study provides the most comprehensive estimate to date of the extent of AM fungal networks across the globe. At the same time, it highlights large areas that have not yet been sampled, underscoring the scale of this vast underground world that has yet to be explored.
Reference: “Global Density and Biomass of Arboreal Fungal Networks” by Justin D. Stewart, Corentin Bisot, Rachel I. M. Cargill, Michael E. Van Noland, Heidi Jane Hawkins, Malin Klein, Mary Van Son, Victoria Terry, Louis Barry, Claudia Pancini, Frank Stefani, Felix Kahani, Kai Kai Lin, Renato K. Pragueri, Katie J. Field, Nadezhda A. Sudzilovskaya, Gensu Ilhans, Vassilis Kokouris, Merlin Sheldrake, James T. Weedon, Thomas S. Shimizu, Stuart West and E. Toby Keres. sciences.
doi: 10.1126/science.adu4373
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