Underground fungi vital to the health of Earth’s ecosystems and climate remain largely unnamed and unknown, with researchers warning that this knowledge gap could undermine global conservation efforts.
A new study published in Current Biology reveals that up to 83% of ectomycorrhizal fungi – a major group that supports plant life and stores enormous amounts of carbon – belong to so-called ‘dark taxa’. These are species detected only through DNA sequences, but which lack formal names or descriptions. Without names, scientists say, it’s nearly impossible to protect them.
Ectomycorrhizal fungi form symbiotic relationships with around a quarter of all plant species, helping them draw nutrients from soil and tolerate environmental stress. In turn, these fungi channel more than nine billion tonnes of carbon dioxide into the soil each year – the equivalent of over a quarter of global fossil fuel emissions, according to the study.
“We are a long way out from getting all fungal DNA sequences linked to named species,” says lead author Laura van Galen, a microbial ecologist at the Society for the Protection of Underground Networks (SPUN).
“Environmental DNA has enormous potential as a research tool to detect fungal species, but we can’t include unnamed species in conservation initiatives. How can you protect something that hasn’t yet been named?”
Dark taxa: mapping global hotspots
In a bid to help reduce this knowledge gap, the study has mapped global hotspots for these unnamed fungi, with high concentrations in tropical forests across southeast Asia, Central and South America, central Africa, and the Sayan montane forests of Mongolia, among others.
Van Galen notes that research remains focused largely in the northern hemisphere, leaving biodiversity-rich southern regions underfunded and underexplored. “Most of the research on ectomycorrhizal fungi has been focused in the North, but mid-latitude and southern-hemisphere regions show signs of being home to many unknown species. This means there is a mismatch in resources and funding. We need to bridge this gap and facilitate more tropical researchers and those from southern-hemisphere regions to focus on identifying these super-important fungi.”
The researchers say there are several approaches that could be taken to help resolve the dark taxa dilemma. “One way to reduce the dark taxa problem is to collect, study and sequence mushrooms and other fungi,” says co-author Camille Truong, a mycorrhizal ecologist at SPUN and research scientist at the Royal Botanic Gardens Victoria in Australia.
“Conversely, there are mushrooms that have been sitting for decades in collections of botanical gardens. These should be urgently sequenced so that we can, hopefully, start matching them up with some of these dark taxa.”
With many of these fungi relying on threatened plants, their future is at risk, say the researchers, who hope this new data will help conservationists to protect vital underground ecosystems.
Main image: underground fungi. Credit: Getty
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