Fungi pull carbon into northern forest soils

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http://www.sciencenews.org/view/generic/id/349265/description/Fungi_pull_carbon_into_northern_forest_soils



The fungus Cortinarius armillatus pulls carbon-rich sugars from tree roots in exchange for water and nutrients. Fungi store substantial amounts of carbon belowground in boreal forests, new research shows.

Sequestration may be questionable fiscal policy, but it means good news in the context of carbon cycles. Vast underground networks of fungi may sequester heaps of carbon in boreal forest soil, a study suggests. By holding onto the element, the fungi do the environment a favor by preventing carbon dioxide from escaping into the atmosphere and warming the planet.

Mycorrhizal fungi, which grow underground in and on tree roots, hold 50 to 70 percent of the total carbon stored in leaf litter and soil on forested islands in Sweden, researchers report March 28 in Science. The new findings poke holes in a long-held idea that carbon in boreal forests accumulates mainly above ground in a litter of pine needles, mosses and leaves. The researchers suggest instead that trees direct carbon deeper into the soil via their root systems.

“It’s hard to quantify how important mycorrhizal fungi are in ecosystems,” says forest ecologist Erik Hobbie of the University of New Hampshire in Durham, who was not involved with the study. “This paper presents hard evidence about their importance.”

Trees suck carbon dioxide from the air and turn the carbon into sugars to fuel growth of branches, leaves and roots. Because trees are so good at capturing carbon dioxide, ecosystems stash loads of carbon in forests. Cold boreal forests are thought to be carbon-storing superstars mostly because litter stacks up on their floors and takes a long time to decompose. These forests stow away nearly a quarter of all the carbon stocked in the Earth’s land surfaces.