Mycorrhizal Management of Atmospheric Carbon

A study published in the January 08, 2014 edition of Nature looked into the relationship of Nitrogen and Carbon storage in soil when compared to atmospheric Carbon as it related to the competition exerted by mycorrhizal fungi. And their studied revealed just how important mycorrhizal fungi (the symbiotic fungi associated with plant roots) are in this relationship.

An important contributor to atmospheric Carbon is the decomposition of organics in the soil by free living microbes.  One of the key resources for these microbes is the availability of Nitrogen, which plants via their mycorrhizal marriages, compete actively for. This would mean that the more active and successful the fungi are at gathering Nitrogen, the less active and successful the free decomposers would be at breaking up organic matter. That, in turn, would lead to an increased storage of Carbon in the Soil.

Amanita phalloides (an Ectomycorrhizal fungi)

Since such a large percentage of plants are associated with fungi of one form or another, this relationship could potentially be hard to determine. Luckily for this study, there are multiple groups of mycorrhizal fungi. The Ectomycorrhizal fungi and ericoid mycorrhizal fungi (EEM), which do a much better job of taking in Nitrogen; and Arbuscular mycorrhizal fungi (AM), which lack the Nitrogen degrading enzyme that makes that it possible.

To study the importance that the mycorrhizal relationship had on Carbon stored in the soil (and thus not in the atmosphere), this group of scientists compared the not only the two above mentioned groups, but also the difference in annual temperature, precipitation, net primary production and clay content, of multiple ecosystems based on global data product measurements.

Their results showed that the EEM ecosystems had a significantly higher storage of Carbon than the AM ecosystems.  When contrasting to the other data measurements, it was determined that the mycorrhizal type was a far more important controller of soil Carbon than the rest.

This means that the Carbon cycle (exchange of carbon throughout the environment) is in part managed by the mycorrhizal control exerted on decomposition in the soil. And as such, the broad implications that could be derived from this study are that changes altering the competition for Nitrogen will also greatly alter the global levels of Carbon in the Atmosphere.

Colin Averill, Benjamin L. Turner, & Adrien C. Finzi (2014). Mycorrhiza-mediated competition between plants and decomposers drives soil carbon storage Nature DOI: 10.1038/nature12901

Photo by Aleksey Gnilenkov (http://www.flickr.com/photos/gnilenkov/5083008614/) [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons