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ARS Home » Plains Area » Temple, Texas » Grassland Soil and Water Research Laboratory » Research » Publications at this Location » Publication #224779
Title: Nonlinear Grassland Dynamics Along a CO2 Gradient

Author
item MANZONI, S - DUKE UNIVERSITY
item Fay, Philip
item KATUL, G - DUKE UNIVERSITY
item PORPORATO, AMILCARE - DUKE UNIVERSITY
item Polley, Herbert

Submitted to: Biological Systems Simulation Group Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 4/30/2008
Publication Date: 7/31/2008
Citation: Manzoni, S., Fay, P.A., Katul, G., Porporato, A., Polley, H.W. 2008. Nonlinear Grassland Dynamics Along a CO2 Gradient. In: Proceedings of the Biological Systems Simulation Group, April 8-9, 2008, Temple, Texas.

Interpretive Summary:

Technical Abstract: Plant photosynthesis and transpiration respond nonlinearly to atmospheric CO2 concentration and vapor pressure deficit, depending on plant water status and thus soil moisture. Modeling vegetation and soil responses to different values of CO2, is critical to predict ecosystem functioning under enriched conditions (as expected in the near future), as well as to understand vegetation dynamics under low CO2 concentrations (during past inter-glacial periods). To this purpose, we developed a general model describing the effects of CO2 concentrations on carbon assimilation and transpiration rates at the half-hourly time scale. The proposed model embeds sub-units describing water and carbon mass balances for each component of the soil-plant-atmosphere continuum, as well as a simplified plant-atmosphere gas exchange scheme. We will apply the model to study carbon and water fluxes in plots containing grassland vegetation on soils from three contrasting soil series exposed to a gradient of [CO2] (250 to 500 µL L-1) in the Lysimeter CO2 Gradient experiment (LYCOG). The short term fluxes of carbon and water in that system will be computed and compared to the fluxes measured along the CO2 gradient. The model will also allow simulation of the responses of carbon and water fluxes to varying temperature, precipitation patterns, and solar radiation, which are not part of the current experiment.