HR: 1340h
AN: B33D-1584    [Abstracts]
TI: Soil Salinity Controls on Water and Carbon Cycling by Sunflower Plants
AU: * Runkle, B
EM: brrunkle@ce.berkeley.edu
AF: Department of Civil & Environmental Engineering, UC Berkeley, 760 Davis Hall, Berkeley, CA 94720-1710, United States
AU: Liang, X
EM: xuliang@engr.pitt.edu
AF: Department of Civil & Environmental Engineering, University of Pittsburgh, 949 Benedum Hall 3700 O'Hara Street, Pittsburgh, PA 15260, United States
AU: Dracup, J
EM: dracup@ce.berkeley.edu
AF: Department of Civil & Environmental Engineering, UC Berkeley, 760 Davis Hall, Berkeley, CA 94720-1710, United States
AU: Hao, F
EM: fanghua@bnu.edu.cn
AF: Department of Environmental Sciences, Beijing Normal University, Beijing, 100875, China
AU: Zeng, A
EM: zengayan@sina.com
AF: Department of Environmental Sciences, Beijing Normal University, Beijing, 100875, China
AU: Zhang, J
EM: lumargenice@yahoo.com.cn
AF: Department of Environmental Sciences, Beijing Normal University, Beijing, 100875, China
AU: He, B
EM: hebin@rainbow.iis.u-tokyo.ac.jp
AF: Institute of Industrial Science, the University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505, Japan
AU: Oki, T
EM: taikan@iis.u-tokyo.ac.jp
AF: Institute of Industrial Science, the University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505, Japan
AB: Agricultural effects on water cycling are of great importance for regional water resources management. These effects vary based on local soil and climate conditions, and are particularly modulated by high soil salinity levels, which stress plant growth and change their water use efficiency. Increasing salinization is predicted under hotter, drier conditions resulting from global climate change and from increased societal pressure on agricultural lands. This increased ionic presence creates a higher soil osmotic pressure that increases the resistance to water flow through the plant. This change also impacts the assimilation of carbon dioxide through the stomatal opening, and so affects rates of both photosynthesis and transpiration. Current agricultural and land-surface models that account for salinity do so in an overly empirical manner that cannot account for changes at different time scales in meteorological conditions. They tend to be ill equipped to examine how changing carbon dioxide levels may modify a plant's response to soil salinity. As a result, we present a new model of soil-vegetation- atmosphere water transfer that explicitly incorporates the role of soil salinity in changing this system's behavior. This model will allow for much greater flexibility in examining how vegetation may change the local water cycle under the joint impacts of both salinity and climate change. This model is supported by field research on the effects of salinity on sunflower plants in a large irrigation district in Inner Mongolia, China. Results presented include the role of salinity in changing stomatal regulation of water use efficiency, sub-canopy changes in leaf pressure, and changes in root activity. Modeling at sub-hourly time scales allows for a more precise understanding of how soil salinity changes the diurnal cycle of plant water use.
DE: 0402 Agricultural systems
DE: 0428 Carbon cycling (4806)
DE: 0466 Modeling
DE: 0495 Water/energy interactions (1878)
DE: 1818 Evapotranspiration
SC: Biogeosciences [B]
MN: 2007 Fall Meeting