The International Union for Conservation of Nature (IUCN) recently updated its Red List of Threatened Species to include an additional 482 fungi, bringing the total to roughly 1,300 species of mushrooms, puffballs and other fungi. More than 400 of the species assessed are at risk of extinction, primarily threatened by agricultural expansion, deforestation and climate change, according to the IUCN’s latest update.

Some 279 fungi species face extinction due to land use change for farming and urbanization, while another 91 species are at risk from agricultural chemicals and pollution.

Meanwhile, deforestation and degradation are driving nearly 200 species toward extinction. Many fungi rely on decaying trees for habitat and “have evolved during millions and millions of years to [use] those specific tree species and those forest habitats,” Anders Dahlberg, a mycology professor with the Swedish University of Agricultural Sciences and a coordinator on the IUCN assessment, told Mongabay. So, when forests are cleared for timber, logging or agriculture, many species of fungi go along with them, he said.

For example, the replacement of native forest with eucalyptus or palm oil plantations can cause a dramatic drop in fungi diversity. Old-growth forests provide continuity for fungi, especially those in symbiotic relationships with plant roots, or mycorrhizal species, which “have their highest fitness in the old-growth forest conditions,” Dahlberg said. For that reason, he said he recommends that at least some stands of old-growth forest should be left intact when forests are logged or developed.

Climate change is a third significant threat to fungi: Rising temperatures and drier conditions have increased the risk for fire, which devastates fungi. “Over 50 fungi species are at risk of extinction due to changes in fire patterns in the USA, which have drastically changed forests,” the report notes.

Despite living largely out of sight, fungi perform a critical role in sustaining life as we know it. “Fungi are the unsung heroes of life on Earth, forming the very foundation of healthy ecosystems,” Grethel Aguilar, IUCN director-general, said in a press release.

Roughly 80% of all plants on Earth have some kind of mycorrhizal symbiosis that allows them to take up nutrients and water, Dahlberb told Mongabay. Without fungi, many plants would struggle to survive.

They are also vital for breaking down dead matter and nutrient cycling in healthy ecosystems. Additionally, many fungi are valuable to humans in their own right; they are used in food, drinks and medicines.

Beyond the many pragmatic reasons to care for the fungi, Dahlberg said there’s also a moral, ethical argument to maintaining fungi diversity. “Small things have the right to live as well as large and strong things,” he said.

Banner image: A collage of mushroom photos. Original images by Steve Axford, Venkatesh Ramamurthi, P.L. Bechly, Harikrishan S., Karode 13 and  J.J. Harrison via Wikimedia Commons  (CC BY-SA 4.0)