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Atmospheric CO2 Enrichment: Working Wonders in the Plant Root Zone
Reference
Fortuna, P., Avio, L., Morini, S. and Giovannetti, M. 2012. Fungal biomass production in response to elevated atmospheric CO2 in a Glomus mosseae-Prunus cerasifera model system. Mycological Progress 11: 17-26.

Background
The authors write that "although considerable attention has been paid to assessing aboveground consequences of increased atmospheric CO2 levels, relatively little is known about associated changes in belowground community dynamics." Thus, they explore a significant aspect of this realm, noting that "one of the most important groups of belowground biota is represented by the symbiotic arbuscular mycorrhizal fungi (AMF), which live in associations with most terrestrial plant species, promoting their growth and health, affecting aboveground community diversity and functioning, and contributing to the regulation of primary productivity (van der Heijden et al., 1998; Smith and Read, 2008)."

What was done
As described by the four Italian researchers, the biomass and length responses of intraradical and extraradical mycorrhizal mycelium under ambient atmospheric CO2 concentrations (aCO2 = 350 or 380 ppm) and elevated CO2 concentrations (eCO2 = 700 or 850 ppm) were investigated using "a non-destructive in vivo experimental model system," wherein "time-course experiments allowed measurements of intact extraradical mycelium spreading from mycorrhizal roots of Prunus cerasifera (purple leaf plum) micropropagated plants inoculated with the arbuscular mycorrhizal fungus Glomus mosseae, in controlled environmental chambers."

What was learned
At the end of the 12-day experiment, it was found that the length of fungal extraradical mycelium had been significantly increased by some 90% by the approximate doubling of the atmospheric CO2 concentration applied, as lengths ranged from 10.7 meters at aCO2 to 20.3 meters at eCO2, while intraradical and extraradical fungal biomass were fully 2 and 3 times larger, respectively, at eCO2 than at aCO2.

What it means
In the words of the scientists who conducted the research, "Glomus mosseae responds to increases of CO2 concentrations producing larger mycorrhizal networks which may potentially represent carbon sink agents in soil ecosystems." And this benefit is in addition to the many other benefits described by van der Heijden et al. (1998) and Smith and Read (2008), as well as those highlighted by many other pertinent papers, reviews of which we have archived in our Subject Index under the general heading of Fungi.

References
Smith, S.E. and Read, D.J. 2008. Mycorrhizal Symbiosis. Elsevier, Amsterdam, The Netherlands.

Van der Heijden, M., Klironomos, J.N., Ursic, M., Moutoglis, P., Streitwolf-Engel, R., Boller, T., Wiemken, A. and Sanders, I.R. 1998. Mycorrhizal fungal diversity determines plant biodiversity, ecosystem variability and productivity. Nature 396: 69-72.

Reviewed 4 July 2012