No responses of belowground C and N pools and dynamics to elevated [CO2], rising temperature and changing soil moisture in old-field grassland.
Wan, Shiqiang1, 2, Norby, Richard2, Weltzin, Jake 3, Allen, Philp3, 1 Institute of Botany, the Chinese Academy of Sciences, Beijing, China2 Environmental Sciences Divsion, Oak Ridge National Laboratory, Oak Ridge, TN, USA3 Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, USA
ABSTRACT- This study was conducted to investigate the effects of atmospheric [CO2], air temperature, and soil moisture on belowground pools and dynamics of C and N in a constructed old-field plant community in east Tennessee. Twelve plots (4 m in diameter) constructed in July 2002 were exposed to combinations of ambient and elevated (+ 300 ppm) [CO2], ambient and elevated (+ 3oC) temperature, and two levels of soil moisture (relatively wet and dry) beginning in June 2003. Root biomass, soil N availability, gross N mineralization, and microbial biomass C and N were measured in 2003 and 2004 using root in-growth cores, resin capsules, 15N dilution, and chloroform fumigation methods, respectively. None of the measured variables showed any responses to [CO2], temperature, or soil moisture. The lack of response in belowground pools of C and N in the first 2 years of the experiment might have been because the plant community was relatively young, or because of changes in species composition. Long-term observations are needed to detect the potential influences of multiple driving factors on pools and dynamics of soil C and N.
Key words: Carbon, Nitrogen, old field, global change
All materials copyright The Ecological Society of America (ESA), and may not be used without written permission.