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Title: Mycorrhizal mediation of soil organic carbon decomposition under elevated atmospheric carbon dioxide

Author
item CHENG, LEI - North Carolina State University
item TU, CONG - North Carolina State University
item Booker, Fitzgerald
item Burkey, Kent
item SHEW, H. DAVID - North Carolina State University
item RUFTY, THOMAS - North Carolina State University
item HU, SHUIJIN - North Carolina State University

Submitted to: Soil Science Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/30/2009
Publication Date: 8/5/2009
Citation: Cheng, L., Tu, C., Booker, F.L., Burkey, K.O., Shew, H., Rufty, T., Hu, S. 2009. Mycorrhizal mediation of soil organic carbon decomposition under elevated atmospheric carbon dioxide. Soil Science Society of America Annual Meeting Nov 2009.

Interpretive Summary:

Technical Abstract: Significant effort in global change research has recently been directed towards assessing the potential of soil as a carbon sink under future atmospheric carbon dioxide scenarios. Attention has focused on the impact of elevated carbon dioxide on plant interactions with mycorrhizae, a symbiotic soil fungus. It has been widely assumed that stimulation of mycorrhizal growth due to enhanced plant productivity at elevated carbon dioxide will increase soil carbon sequestration through the facilitation of soil aggregation and reduced carbon mineralization. However, the role of mycorrhizal fungi in organic matter decomposition in response to global change factors has not been carefully assessed. Here we present results from two independent but complementary experiments illustrating that the carbon dioxide-related enhancement of mycorrhizal growth increased decomposition, positively feeding back carbon dioxide to the atmosphere. Results from 15N tracer measurements also indicated that elevated carbon dioxide considerably increased mycorrhizally-mediated plant nitrogen acquisition from decomposing residues. These findings directly challenge the current view that increasing mycorrhizal fungi with rising carbon dioxide could increase soil carbon sequestration. They also suggest that increased mycorrhizal fungal growth might shortcut the soil nitrogen cycle by increasing plant nitrogen acquisition from decomposing residues under elevated carbon dioxide concentration, especially in nitrogen-poor soils, thereby reducing nitrogen limitations on ecosystem responses to elevated carbon dioxide concentrations.