New Study Reveals Mycorrhizal Fungal Hotspots and Their Lack of Protections – Inside Climate News

In the soils of most ecosystems around the world, mycorrhizal fungal communities form intimate relationships with the roots of the plants above them, exchanging nutrients like phosphorus and nitrogen for carbon, of which they store an estimated 13 billion tons annually.

But with mycorrhizal fungi living underground, science’s understanding of their global distribution has lagged behind what it knows about plants and animals found on the surface. A new study published Wednesday in Nature helps to change that, with the Society for the Protection of Underground Networks mapping the global distribution of mycorrhizal fungi’s biodiversity for the first time. But the progress came with some bad news, as the study found that more than 90 percent of fungal communities are unprotected, threatening their ability to draw down carbon and support ecosystems across the globe. 

“They’re just this key missing piece to not only our ability to protect biodiversity, but also to protect healthy, resilient ecosystems,” said Michael Van Nulan, the lead author of the paper, a data scientist at SPUN, and an ecologist and evolutionary biologist.

The study charts the world’s underground mycorrhizal fungal communities, complete with interactive maps available to the public and the code for the data fully available to other researchers to pave the way for further research in the field. Pulling together 2.8 billion genetic sequences of fungi sampled from 130 countries, the researchers used machine learning to uncover the relationships between mycorrhizal diversity and environmental conditions.

From there, Van Nulan said, the model can make “predictions about not only what’s the diversity of areas that you’ve sampled, but what’s the expected diversity in all the places you haven’t sampled yet” 

Major hotspots of fungal richness were found across the savannas of the Brazilian Cerrado, tropical forests across Southeast Asia and Guinean forests in West Africa, while areas with high levels of unique, endemic species were found in tropical and subtropical forests in the Congo Basin and eastern Amazon basin. 

Mycorrhizal fungi form intimate symbiotic relationships with roughly 80 percent of the globe’s plant species as they entwine themselves with the plants and their roots, Van Nulan said, relationships scientists are just beginning to unravel. Even most houseplants have fungi growing with them whose spores can enter the air. 

“But the fungi themselves are more than just like a neat accessory to plants,” he said. “They have their own interesting lives. They send these fungal networks out into the soil, and they’re mining for nutrients and resources. They’re living and growing and fusing and interacting with all the diversity of the soil food web, and at their core, they really form a central basis to this idea of soil health.”

Notably, the study found that at a global scale, plant diversity is not a straightforward indicator of mycorrhizal fungal biodiversity. That would indicate that protecting the widest range of plants in a given ecosystem might not help protect fungal networks below the surface. “If plant diversity is not a direct indicator of mycorrhizal fungal diversity, then protecting underground biodiversity requires explicit consideration that is based on the development of new high-resolution identification and monitoring approaches,” the researchers wrote in the study. 

The researchers found that less than 10 percent of mycorrhizal fungal communities have any sort of protections—roughly three times less than plants and animals. Van Nulan said the study is the first step in getting mycorrhizal fungi a seat at the table to gain protection and highlights the benefits they bring to biodiversity and climate change for a wider audience. 

“Restoration practices have been dangerously incomplete because the focus has historically been on life aboveground,” said Alex Wegmann, a lead scientist for The Nature Conservancy, in a statement. “These high-resolution maps provide quantitative targets for restoration managers to establish what diverse mycorrhizal communities could and should look like.”

Van Nulan said the research on the distribution and protection of mycorrhizal fungi has been core to SPUN’s work since he was hired three years ago. It was only possible due to the use of open source data and extensive hours of work in the field and the lab by both the SPUN team members and others whose work they draw from, to collect soil samples, sequence the DNA of the fungi in it and use machine learning to build global maps of mycorrhizal fungal hotspots. 

The publishing of the paper opens a new door for SPUN to begin “ground truthing” the research, Van Nulan said, by going out into the field and exploring the newly discovered hotspots and even areas with little biodiversity, to further investigate the connections these fungal communities have, or don’t, across ecosystems.

The new study also poses a question: Do our current methods of protecting landscapes, like creating national parks or designating wilderness areas, work for mycorrhizal fungi the same way they do for plants and animals?

“We’ve exposed a conservation gap with this analysis—less than 10 percent of biodiversity hotpots are currently protected,” Van Nulan said. “It’s a really interesting starting point to go off of. But if we want to protect them more, do we set up protected areas or not? Do we set up networks of protected areas … Or do we need new approaches? And what would those new approaches look like?”