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Title: Effects of atmospheric CO2 enrichment on soil CO2 efflux in a young longleaf pine system

Author
item Runion, George
item BUTNOR, J - US Department Of Agriculture (USDA)
item Prior, Stephen - Steve
item MITCHELL, ROBERT - Non ARS Employee
item ROGERS, HUGO - Retired ARS Employee

Submitted to: International Journal of Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2012
Publication Date: 3/14/2012
Citation: Runion, G.B., Butnor, J.R., Prior, S.A., Mitchell, R., Rogers, H.H. 2012. Effects of atmospheric CO2 enrichment on soil CO2 efflux in a young longleaf pine system. International Journal of Agronomy. vol. 2012, Article ID 549745, 9 pages, doi:10.1155/2012/549745.

Interpretive Summary: Understanding how the rise in global atmospheric carbon dioxide (CO2) affects carbon released back to the atmosphere is critical to knowing how much carbon can be stored in soil. Soil CO2 losses were monitored in a young longleaf pine system exposed to two levels of atmospheric CO2 (ambient or elevated). Our results suggest that soil CO2 losses were higher under elevated atmospheric CO2; however, since longleaf pines grew larger under elevated CO2, these forests can still be sinks for atmospheric CO2.

Technical Abstract: Elevated atmospheric carbon dioxide (CO2) can affect the quantity and quality of plant tissues which will impact carbon (C) cycling and storage in plant/soil systems and the release of CO2 back to the atmosphere. Research is needed to quantify the effects of elevated CO2 on soil CO2 efflux to predict the potential of terrestrial ecosystems to sequester C. We investigated the effects of ambient and elevated atmospheric CO2 on soil CO2 efflux in a young longleaf pine system using a continuous soil CO2 efflux monitoring system. A significant increase (26.5 %) in soil CO2 efflux across 90 days was observed under elevated CO2; this occurred for all weekly and daily averages except for two days when soil temperatures was lowest. Soil CO2 efflux was positively correlated with soil temperature with a trend towards increased efflux response to temperature under elevated CO2. Soil CO2 efflux was negatively correlated with soil moisture and was best represented using a quadratic relationship. Soil CO2 efflux was not correlated with root biomass. Our data indicate that, while elevated CO2 will increase feedback of CO2 to the atmosphere via soil efflux, terrestrial ecosystems remain potential sinks for atmospheric CO2 due to greater biomass production and increased soil C sequestration. [GRACEnet Publication]