HR: 0800h
AN: B31B-0323    [Abstracts]
TI: Impacts of an Anomalously Warm Year on Soil Nitrogen Availability in Experimentally Manipulated Intact Tallgrass Prairie Ecosystems
AU: * Verburg, P S
EM: Paul.Verburg@dri.edu
AF: Desert Research Institute Division of Earth and Ecosystem Sciences, 2215 Raggio Parkway, Reno, NV 89512, United States
AU: Johnson, D W
EM: dwj@cbnr.unr.edu
AF: Department of Environmental and Natural Resource Sciences University of Nevada, Reno, 1000 Valley Road, Reno, NV 89512, United States
AU: Schorran, D E
AF: Desert Research Institute Division of Earth and Ecosystem Sciences, 2215 Raggio Parkway, Reno, NV 89512, United States
AU: Wallace, L L
EM: lwallace@ou.edu
AF: Department of Botany and Microbiology University of Oklahoma, 770 Van Vleet Oval, Norman, OK 73019, United States
AU: Luo, Y
EM: yluo@ou.edu
AF: Department of Botany and Microbiology University of Oklahoma, 770 Van Vleet Oval, Norman, OK 73019, United States
AU: Arnone, J A
EM: jarnone@dri.edu
AF: Desert Research Institute Division of Earth and Ecosystem Sciences, 2215 Raggio Parkway, Reno, NV 89512, United States
AB: Modeling analyses suggest that changes in the growth rate of atmospheric CO₂ concentrations in response to an anomalously warm year may be caused by warming-induced increases in nitrogen (N) availability feeding back to net primary productivity (NPP), and ultimately net ecosystem productivity (NEP). To test this hypothesis, twelve intact soil monoliths were excavated from a tallgrass prairie site in Oklahoma, USA and divided among four large dynamic flux chambers (EcoCELLs) allowing for direct measurement of NEP. During the first year, all EcoCELLs were subjected to Oklahoma climate conditions. During the second year, air temperature in two EcoCELLs was increased by 4°C. During the third and fourth year temperatures in the warmed EcoCELLs returned back to ambient conditions. We used several methods to assess soil N availability including plant N uptake, soil solution and drainage chemistry and resin techniques (resin capsules and plant-root simulator (PRS) probes). During the warming and first post-warming year, plant N content in the warmed EcoCELLs increased relative to the controls indicating that soil N availability increased in response to warming. Despite increased N availability, NEP decreased during the warm year most likely due to a drought-induced reduction in NPP. The PRS probes showed increased N availability during the summer of the warm year but none of the other measurements showed any effect of the warming. Both resin techniques correlated well with each other but correlations between resin techniques and plant N were limited. In general, PRS N was negatively correlated with plant N indicating that the PRS probes capture ‘leftover N' after plant demand was satisfied.
DE: 0400 BIOGEOSCIENCES
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0428 Carbon cycling (4806)
DE: 0469 Nitrogen cycling
DE: 0470 Nutrients and nutrient cycling (4845, 4850)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting