274-9 Mineralization of Carbon Stored In the Soil of Forests After Exposure to Elevated Concentrations of Atmospheric Carbon Dioxide and Ozone.



Tuesday, October 18, 2011: 3:30 PM
Henry Gonzalez Convention Center, Ballroom C-2, Ballroom Level

Robert Qualls1, Kurt S. Pregitzer2 and Courtney Campany2, (1)MS-370 121 Fleishmann Agriculture Bldg, University of Nevada - Reno, Reno, NV
(2)Univerisity of Idaho, Moscow, ID
Large scale Free Air Carbon Enrichment experiments have shown that generally there is a substantial increase in forest tree productivity when trees are exposed to elevated atmospheric CO2. It is often assumed that this increase in productivity will result in increased C storage in the soil, thus partially mitigating the rise in atmospheric CO2. We measured C mineralization rates in soils taken from forest plots exposed to either: ambient conditions, elevated CO2, elevated ozone, or elevated CO2 plus ozone for 12 years. Soils were incubated for one year and the rate of C mineralization was measured. C isotope ratios were also measured in the respired CO2 to detect the fate of the added CO2 used during fumigation. The percentage of soil C mineralized during the incubation was significantly greater in soils from CO2 enriched plots, but it was not enough to account for the fate of the increased production in CO2 enriched plots. The percentage of soil C mineralized was also significantly greater in soils from CO2 and Ozone enriched plots. However, a substantial amount of C originating from the CO2 enrichment remained in the refractory fraction of soil C.
See more from this Division: S07 Forest, Range & Wildland Soils
See more from this Session: Carbon and Nutrient Cycling