Stop for a minute and picture a few endangered species. What came to mind? For most, it’s probably charismatic animals like a wolf, condor or dolphin. Some might go a bit further and think of insects, like monarch butterflies. Perhaps plants—rare orchids, ancient redwoods.

But will anyone think of a soil-dwelling fungi? I thought not.

Now maybe you will, if a group of scientists get their way. They just released a global map of mycorrhizal fungi, along with a paper in Nature that documents a troubling phenomenon. While these fungi are critical to plant health and sequestering carbon, less than 10% of the most species-rich spots on the planet enjoy any official protection.

“For centuries, we’ve mapped mountains, forests, and oceans. But these fungi have remained in the dark,” said Toby Kiers, an evolutionary biologist and executive director of the Society for the Protection of Underground Networks (SPUN), which created the new map. “This is the first time we’re able to visualize these biodiversity patterns—and it’s clear we are failing to protect underground ecosystems.”

It’s easy to see why they have gone under appreciated. These organisms form hairlike underground networks that are easy to overlook. Even if you are digging around in the soil, you might not notice a handful of tiny white threads in a spadeful of dirt.

Despite their invisibility, these fungi are biological marvels critical to life on the planet. They form vast interconnected systems that shuttle nutrients such as nitrogen and phosphorous to plants, while collecting carbon in return. Scientists have tracked how these seemingly simply organisms can form smart “waves” that spread through the soil, homing in on the most promising plant roots. At least 80% of plant species are known to be plugged into these networks. The carbon funneled into the soil by these fungi totals 3.6 billion tons per year, a third of global fossil fuel emissions.

But a lot isn’t known about these species and their health. A tiny fraction – .001% – of the Earth’s surface has been sampled in the search for mycorrhizal fungi. To begin assembling a more complete picture, scientists with SPUN and universities around the world turned to artificial intelligence.

They compiled data from 25,000 soil samples containing more than 2.8 billion fungal DNA sequences representing more than 150,000 different species. They then used that information to train a high-powered computer model to predict where the different fungi are likely to occur across the planet. The model took into two dozen different factors that seemed to influence what fungi turned up in a bit of soil, including soil chemistry and structure, climate variables such as average temperature and rainfall, the types of vegetation and the geography. The result is a set of digital maps that predict the mycorrhizal fungi of the Earth’s land surface broken into 1-kilometer squares.

These maps reveal that not all parts of the planet are created equal. Some places stand out for the rich variety of soil fungi or for the high numbers of unique, rare fungi. Those locations vary depending on the type of fungi. Arbuscular mycorrhizae (AM), which integrate themselves inside the cells of plant roots, are the most common, found in around 80% of all plants, including crops, grasslands and tropical forests. Their hotspots are concentrated in tropical regions of South America, Africa and Asia. Less common ectomycorrhizae (EcM) form a sheath around a plant’s roots, rather than penetrating the root cells. They are concentrated in cooler places like boreal forests in Canada and Siberia. Some of the rarest ectomycorrhizae, however, are predicted to be in far flung places including northern tundra, mountain forests in Indonesia and conifer forests in Central America.

While the maps reveal these fungi occur just about anywhere you find plants, it also shows that places with the richest or rarest fungal communities frequently lie outside protected areas such as national parks. Just 9.5% of the most biodiverse fungal hotspots occurred in land with some kind of protection. The picture for the rarest collections was slightly better, with 23% of those places protected.

It’s perhaps no big surprise that conservation efforts up to this point haven’t focused on species that, though important, are largely invisible and not very charismatic. Scientists involved in the project hope these new maps will call attention to what’s underfoot, and help make future decisions about where to protect or restore ecosystems more fungi-friendly.

“For too long, we’ve overlooked mycorrhizal fungi,” said Merlin Sheldrake, a biologist, SPUN member and author of the bestselling book about fungi, Entangled Life. “These maps help alleviate our fungus blindness and can assist us as we rise to the urgent challenges of our times.”

Van Nuland, et. al. “Global hotspots of mycorrhizal fungal richness are poorly protected.” Nature. July 23, 2025.

Image: ©Anthropocene Magazine/AI-generated