HR: 1340h
AN: B33D-1572    [Abstracts]
TI: Will stomatal behavior lead to a positive or negative feedback to anticipated climatic change?
AU: * Pavlick, R
EM: rpavlick@bgc-jena.mpg.de
AF: Max Planck Institute for Biogeochemistry, Postfach 10 01 64, Jena, 07745, Germany
AU: Kleidon, A
EM: akleidon@bgc-jena.mpg.de
AF: Max Planck Institute for Biogeochemistry, Postfach 10 01 64, Jena, 07745, Germany
AB: Some coupled climate-vegetation models use the Ball-Berry empirical relationship to simulate the effect of environmental conditions on stomatal conductance. This can lead to a positive feedback in the model, wherein the simulated vegetation closes its stomates due to higher pCO2 concentrations or water stress, resulting in less moisture cycling, enhancing stomatal closure, and eventually contributing to a non-vegetated state. Previous studies at the leaf, canopy, and regional scales have suggested that stomata function optimally to maximize carbon gain. Optimal stomatal functioning would suggest that stomata will react with a negative feedback to climatic change. Here we compare three transient climate-vegetation simulations forced with prescribed pCO2 concentrations over the 1850 -2100 time period. In the control simulation, we maximize the gross primary productivity with respect to the stomatal conductance parameter for pre-industrial conditions. This parameter is then held constant for the remainder of the simulation. In another simulation, we optimize the stomatal conductance parameter at regular intervals throughout the simulation period. In a third simulation, the stomatal conductance is calculated according to the Ball-Berry relationship. We then evaluate the simulations with regards to the modeled productivity and associated surface and boundary-layer characteristics.
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 0428 Carbon cycling (4806)
DE: 1615 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 4805, 4912)
DE: 1622 Earth system modeling (1225)
DE: 1813 Eco-hydrology
SC: Biogeosciences [B]
MN: 2007 Fall Meeting