CO2 Effects on Micronutrients in Plants
Natali, S.M., Sañudo-Wilhelmy, S.A. and Lerdau, M.T. 2009. Plant and soil mediation of elevated CO2 impacts on trace metals. Ecosystems 12: 715-727.
To explore these contrasting views of the subject, Natali et al. "examined CO2 effects of a suite of metal micronutrients and contaminants in forest trees and soils at two free-air CO2 enrichment sites -- a loblolly pine forest in North Carolina (Duke) and a sweetgum plantation in Tennessee [Oak Ridge National Laboratory (ORNL)] -- and an open-top chamber experiment in a scrub-oak community in Florida [Smithsonian Environmental Research Center (SERC)]."
The three U.S. researchers report that they "did not find an overall decline in foliar metal concentrations with CO2 enrichment," but that they did find that dilution effects for metal micronutrients were generally "less than for non-essential trace metals," and that "some essential plant metals were greater under elevated CO2 (for example, 28% increase in Mn across species and sites)."
Natali et al. thus conclude that their results "should alleviate some concerns that rising CO2 concentrations will result in broad-scale decreases in the concentrations of all elements essential for plant function and animal nutrition," as proposed by Loladze (2002). They also say their generally opposite results for non-essential trace elements (some of which can be toxic) "may be applicable to contaminated systems," stating that "elevated CO2 may, through dilution effects, alleviate aluminum toxicity." In general, therefore, one could say that elevated CO2 tends to increase the availability of helpful trace elements, while it tends to decrease the availability of harmful ones.
Loladze, I. 2002. Rising atmospheric CO2 and human nutrition: toward globally imbalanced plant stoichiometry? Trends in Ecology and Evolution 17: 457-461.
Norby, R.J., Ledford, J., Reilly, C.D., Miller, N.E. and O'Neill, E.G. 2004. Fine-root production dominates response of a deciduous forest to atmospheric CO2 enrichment. Proceedings of the National Academy of Sciences, USA 101: 9689-9693.
Pritchard, S.G., Strand, A.E., McCormack, M.L., Davis, M.A., Finzi, A., Jackson, R.B., Matamala, R., Rogers, H.H. and Oren, R. 2008. Fine root dynamics in a loblolly pine forest are influenced by free-air-CO2-enrichment: a six-year-minirhizotron study. Global Change Biology 14: 588-602.