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The Respiratory Response of Ectomycorrhizal Fungi to Warming
Reference
Malcolm, G.M., Lopez-Gutierrez, J.C., Koide, R.T. and Eissenstat, D.M. 2008. Acclimation to temperature and temperature sensitivity of metabolism by ectomycorrhizal fungi. Global Change Biology 14: 1169-1180.

Background
There is a concern in some circles that CO2-induced global warming will lead to an increase in ecosystem respiration, resulting in more CO2 being released to the atmosphere, which phenomenon promotes still further warming in a vicious positive feedback cycle that pushes earth's surface air temperature ever higher.

What was done
The authors examined acclimation of respiration to rising temperature in ectomycorrhizal (ECM) fungi -- which form mutualistic relationships with the roots of trees and shrubs in boreal, temperate and tropical ecosystems -- by incubating twelve ECM fungal isolates for one week at three different temperatures and subsequently measuring their rates of respiration at warmer temperatures.

What was learned
Malcolm et al. report that of the twelve fungal isolates tested, three exhibited significant acclimation to temperature, "exhibiting an average reduction in respiration of 20-45% when incubated at 23C compared with when incubated at 11 or 17C."

What it means
The four researchers concluded that "substantial variation exists among ECM fungal isolates in their ability to acclimate to temperature," and that those isolates that acclimate "may require less carbon from their host plants than fungi that do not acclimate." In addition, they write that this acclimation "could ameliorate the effect of warming on soil respiration, to which ECM fungi contribute significantly." Consequently, they say that "as global temperatures increase, the ability to acclimate respiration to temperature by ECM fungi could partially ameliorate the positive feedback between soil respiration and temperature and reduce the carbon demand by ECM fungi upon their plant hosts."

Reviewed 9 July 2008