Mycorrhizal fungi have supported life on Earth for at least 450 million years by helping to supply plants with soil nutrients necessary for growth. In recent years, scientists have found that in addition to forming symbiotic relationships with nearly all land plants, these fungi are important channels for transporting carbon into soil ecosystems.
In a meta-analysis published June 5 in the journal current biology, Scientists estimate that up to 13.12 gigatonnes of carbon dioxide equivalent (CO2e) installed by terrestrial plants is for mycorrhizal fungi annually – roughly equivalent to 36% of annual global fossil fuel emissions.
Since 70% to 90% of land plants form symbiotic relationships with mycorrhizal fungi, researchers have long believed that there must be a significant amount of carbon moving into the soil through their webs.
“We always suspected we might be overlooking a large carbon pool,” says author Heidi Hawkins, research leader at Conservation South Africa and research associate in soil-microbe interactions at the University of Cape Town. “Understandably, much emphasis has been placed on protecting and restoring forests as a natural means of mitigating climate change. But little attention has been paid to the fate of the vast amounts of carbon dioxide that is carried out of the atmosphere during photosynthesis by those plants and sent underground to Mycorrhizal fungi.”
Mycorrhizal fungi transfer mineral nutrients to carbon and obtain it from their plant partners. These bidirectional exchanges are made possible by the associations between mycorrhiza, the thread-like filamentous networks that make up the bulk of fungal biomass, and plant roots. Once transported underground, the carbon is used by mycorrhiza to grow more extensive mycorrhiza, which helps them explore the soil. It is also bound to the soil by sticky compounds secreted by fungi and can remain underground as a mycorrhizal mass, which serves as a structural scaffold for the soil.
Scientists know that carbon flows through fungi, but how long it stays there is still not clear. “A big gap in our knowledge is the persistence of carbon within fungal root structures. We know that it flows, with some being retained in fungal structures during the fungus’ life, and even after it dies,” says Hawkins. “Some of it will break down into small carbon molecules and from there either bind to molecules in the soil or even be reused by plants. Certainly, some of the carbon will be lost as carbon dioxide during respiration by other microbes or the fungi themselves.”
The paper is part of a global push to understand the role fungi play in Earth’s ecosystems. “We know that mycorrhizas are very important to ecosystem engineers, but they are not visible,” says senior author Tobi Kerz, professor of evolutionary biology at Vrije Universität Amsterdam and co-founder of the Society for the Protection of Underground Networks (SPUN). “Mycorrhiza fungi lie at the base of food webs that support much of life on Earth, but we’re only just beginning to understand how they really work. There’s still a lot to learn.”
But there is a race against time to understand and protect these fungi. The Food and Agriculture Organization of the United Nations has warned that 90% of soils could be degraded by 2050, and that fungi are excluded from most conservation and environmental policies. Without the fertility and structure that soil provides, the productivity of both normal plants and crops will decline rapidly.
“Mycorrhizal fungi represent a blind spot in carbon modeling, conservation and restoration,” says co-author Katie Field, Professor of Plant Soil Processes at the University of Sheffield. “Soil ecosystems are being destroyed at an alarming rate by agriculture, development and other industries, but the broader effects of the disruption of soil communities are poorly understood. When we disrupt ancient life-support systems in soils, we sabotage our efforts to limit global warming and undermine the health and resilience of the ecosystems on which we depend. on her “.
“Many human activities destroy underground ecosystems. Besides reducing destruction, we need to radically increase the rate of research,” says co-author Merlin Sheldrake. Organizations like weaveAnd Fungi FoundationAnd GlobalFungi They lead a massive global sampling effort to create open-source maps of Earth’s fungal networks. These maps will help characterize underground ecosystems, such as carbon sequestration hotspots, and document new fungal species that are able to withstand drought and high temperatures.”
The researchers stress that although their figures are based on the best evidence available, they are incomplete and should be interpreted with caution. “Although our numbers are only estimates, they are the best we can provide with the available data. The limitations of our study demonstrate the urgent need for further empirical study of carbon and nutrient fluxes between plants and mycorrhizal fungi,” says Sheldrake. .
mycelium mycorrhizal as a global carbon pool, Current Biology (2023). DOI: 10.1016/j.cub.2023.02.027
the quote: Fungi store a third of the carbon of fossil fuel emissions and may be necessary to reach net zero, new study reveals (2023, June 5) Retrieved June 5, 2023 from https://phys.org/news/2023-06-fungi-emissions Carbon – a fossil fuel. html
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