Martinez-Suz’s research focuses on mycorrhizae, a large group of fungi that coexist with plant root systems. They form networks that travel around and sometimes inside plant roots, transporting nutrients and water to the plant in exchange for carbon. About 90 percent of plant species are known to form such symbiotic trading networks with different fungal species. “These plants are covered in these fungi. It’s incredible. The fungi are tiny, but they’re everywhere,” says Martinez-Suz.
This has significant implications for reforestation programmes: planting new forests is the best hope for carbon sequestration, but there is growing evidence that mycorrhizal networks may be essential to the success of these endeavours. One reforestation study found that birch and pine forests planted on moors in northern Scotland did not increase soil carbon stocks almost 40 years after they were buried. The researchers who carried out the study believe that this may be because the influx of new trees disrupted the delicate mycorrhizal networks of the moors that were already there.
“Replacing an entire fungus with another has implications for long-term carbon sequestration and biodiversity in soils,” says Martinez-Süss. Her current project is comparing forest samples from less polluted areas, like northern Finland, with those from more heavily polluted areas, like Belgium and the Netherlands. Fungal diversity is lower in the polluted areas, which could have a knock-on effect on the forest’s carbon storage efficiency, she says.
The main culprit here is nitrogen pollution, which gets into the soil through the burning of fossil fuels for electricity and transport, and through agriculture. Excess nitrogen changes the composition of soil fungi, reducing the number of fungi that are best suited to retaining nutrients and pumping carbon into the soil.
But there’s hope that forests can turn things around: One study in the Netherlands found that beneficial fungi began to return to forests when nitrogen pollution was reduced. Martinez Sues says the danger is that if ecosystems become too degraded, fungal spores may persist and not be able to multiply.
We need to know all these species to better understand how these fungi affect important ecosystems. Mycologists believe that about 90 percent of the world’s fungi have yet to be discovered. Kew Gardens archivists are only halfway through a lengthy process of digitizing their collections so that researchers can easily learn where and when fungi have been found.
About 5,000 additional specimens are brought into the mycology museum each year, and shelves are full of specimens waiting to be dried and stored. Davis says many of them are sent in by amateur mycologists who are fascinated by the world of fungi. “People from these academic institutions send them specimens to work on and identify, because they’re world-class experts, even though they have no formal training. They’re really dogged. It’s really amazing.”
This article appears in the July/August 2024 issue. WIRED UK magazine.
