Climate Change in the News: "Why Some Mushrooms May Be Magic for Climate Change" (TIME Magazine)

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Summary: Plants draw carbon dioxide from the air. When they die, they deposit carbon in the soil. This carbon is returned to the air as microbes in the soil decompose dead plant matter. However, the rate of decomposition depends on the availability of nitrogen in the soil: less nitrogen means less microbial activity and a slower rate of re-emission of carbon from the soil into the atmosphere. Crucially, plants also need nitrogen, and, according to the article, "Most plants have a symbiotic relationship with mycorrhizal fungi: the fungi extract the nitrogen from the soil, and make it available to the plants through their roots." A new study by Averill, Turner, and Finzi (published Jan 1, 2014) shows that, of the two main types of mycorrhizal fungi—ecto/ericoid (EEM) and arbuscular (AM)—EEM-dominated soils store 70% more carbon. They also show that this trend is independent of, and—as far as carbon storage in the soil is concerned—more significant than the effects of net plant growth, temperature, precipitation, and soil clay content. So the effect of fungus type on soil carbon content is significant on a global scale.

Original study: "Mycorrhiza-mediated competition between plants and decomposers drives soil carbon storage"

Graph from study comparing the two types of fungi with respect to nitrogen fixation and carbon storage in the soil

Averill, the lead author of the paper, further claims that fungus type is an important factor to consider in climate models and future carbon dioxide level predictions.
Could we use EEM fungus to slow the increase of carbon dioxide levels and curb global warming? Well unfortunately, 85% of plant families are adapted to symbiotic relationships with AM fungi, while just a few plant families have symbiotic relationships with EEM fungi. But soils are definitely a major carbon sink, and they may regardless be key to reducing carbon dioxide levels.

Colin Averill, Benjamin L. Turner, and Adrien C. Finzi. (n.d.). Mycorrhiza-mediated competition between plants and decomposers drives soil carbon storage. Nature. doi:10.1038/nature12901
Bryan Walsh. Why Some Mushrooms May Be Magic for Climate Change. Time Magazine.