Pollution and deforestation pushing fungi towards extinction

Fungi are at risk of being wiped out before we even know much about them.

Everything from food security to soil fertility relies on these organisms, which recycle essential nutrients through the ecosystems.

But of an estimated 2.5 million species of fungi thought to exist, scientists have only studied 155,000, and just 1,300 have made it into the International Union for the Conservation of Nature’s (IUCN) Red List. This list is a global record of the conservation status of organisms, highlighting those most at risk of going extinct.

While the red listing of more mushrooms and their relatives has been welcomed, the results paint a worrying picture. Almost a third of fungi on the Red List are in danger of extinction, with pollution, habitat destruction and climate change among the leading threats.

But with so many species still to be named, let alone assessed, the group could be in even more peril than we realise. Dr Grethel Aguilar, the IUCN’s Director General, says that research is urgently needed to understand and protect these organisms.

"Fungi are the unsung heroes of life on Earth, forming the very foundation of healthy ecosystems – yet they have long been overlooked,” Grethel says. “Thanks to the dedication of experts and community scientists, we have taken a vital step forward: over 1,000 of the world’s 155,000 known fungal species have now been assessed for the IUCN Red List of Threatened Species”.

“Now, it’s time to turn this knowledge into action and safeguard the extraordinary fungal kingdom, whose vast underground networks sustain nature and life as we know it.”

Why are fungi important?

Mushrooms, yeasts and mould are all different examples of fungi. While these organisms have characteristics of both plants and animals, they’re part of their own section of the tree of life.

Microbes aside, fungi is the second largest of the kingdoms of life after animals. In part, this is due to their ability to adapt to all kinds of lifestyles – from taking over the minds of ants to feeding on radiation that would kill many other forms of life.

One of the main roles of fungi is in nutrient cycling. Mycorrhizal fungi, for example, form networks around plant roots that provide nutrients like nitrogen and phosphorus in return for sugars from the plant.

When organisms die, fungi are also some of the planet’s main decomposers. They are particularly important for breaking down wood and other plant material which are otherwise very resistant to degradation.

Humans also make use of fungi for food, whether it’s making bread rise, fermenting drinks or eating them directly. They’re also important for making medicines and can help to clean up contaminated sites.

But despite their importance, fungi don’t get much conservation attention. The most recent update to the Red List is the first time that the conservation status of more than 1,000 fungi species has been assessed. Nonetheless, there’s still a long way to go.

The threats facing fungi

Of the 1,300 fungi that are now on the Red List, 411 are at risk of extinction. The major threat is habitat loss, with the growth of cities and farmlands removing the moist environments that many fungi need to thrive.

The loss of forests is having a particular impact, with 198 species threatened by both legal and illegal logging. One threat hotspot is the old-growth pine forests of Scandinavia and Russia, as 30% of these woodlands have been lost since 1975.

As these ancient forests are replaced by tree plantations, slower-growing fungi don’t have time to fully re-establish before the trees are cut down and replanted. This has led to species such as the giant knight, Tricholoma colossus, being classed as Vulnerable by the IUCN.

Professor Anders Dahlberg, who co-ordinates the red listing of many fungi species, says that the loss of these species impacts the lives of many plants and animals.

“As we lose fungi, we impoverish the ecosystem services and resilience they provide, from drought and pathogen resistance in crops and trees to storing carbon in the soil,” Anders explains.

“It is important that more old-growth forests are protected. Forestry practices should consider fungi, for example leaving dead wood and scattered trees, and proactive forest management can help manage fire intensity.”

Fires are a particular issue for fungi in the USA, where over 50 species are at risk of extinction due to climate change. Gastroboletus citrinobrunneus, for example, has seen its home in the Sierra Nevada mountains subjected to droughts, wildfires and invasive insects that have led to it being classed as Endangered.

Over in Europe, meanwhile, pollution has emerged as a particular concern. While fungi are used to cycling nutrients, they are increasingly being overwhelmed by the amount of additional nutrients that humans are releasing into the environment.

Some of the main sources of nutrient pollution are fertiliser runoff and exhaust fumes, which add large amounts of nitrogen to the land and waterways. The impact of this has led to the fibrous waxcap, a relatively widespread mushroom in Europe, now being classed as Vulnerable.

It’s likely that many more species will join the waxcap in the threatened sections of the Red List as our knowledge of fungi improves. Turning their fortunes around will mean taking greater steps to tackle the joint crises of climate change and biodiversity loss.