HR: 0800h
AN: H51D-05    [Abstracts]
TI: Regulation of Soil Moisture on Water Transport in an Oak Savanna Ecosystem at Plant and Stand Scales
AU: * Chen, X
EM: chenxy@berkeley.edu
AF: Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720, United States
AU: * Chen, X
EM: chenxy@berkeley.edu
AF: Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720, United States
AU: Rubin, Y
EM: rubin@ce.berkeley.edu
AF: Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720, United States
AU: Baldocchi, D D
EM: baldocchi@nature.berkeley.edu
AF: Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720, United States
AU: Miller, G
EM: gmiller@berkeley.edu
AF: Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720, United States
AB: Study of water exchange between soil, plant and the atmosphere in response to seasonal or periodic droughts is critical to model the hydrologic cycle and many other processes in water-controlled ecosystems. The difficulties in such studies arise from insufficient understanding of the complex interactions between the various processes and their scale-dependence. The purpose of our study is to investigate the regulation of root water uptake and evaporative fluxes by water deficits and climatic conditions at a plant scale (a few m2) and at a stand scale (a few hundreds to a few thousands m2). Our study site is an oak savanna ecosystem that is located in Mediterranean climate zone and experiences annual summer droughts. The influence of soil moisture on actual evapotranspiration (ET) at the stand scale is studied using spatially distributed soil moisture measurements and tower-based ET measurements, and it is separately investigated for trees, grasses and mixture of trees and grasses in the ecosystem. On the other hand, study at the plant scale is based on stem sap flow measurements using the heat ratio method and soil moisture measured in the local root zone. Potential tree transpiration and stand-level ET are estimated from meteorological variables using the Penman-Monteith equation. The regulation patterns of soil moisture on water transport at the plant and stand scales are studied by examining the change of ratio between the actual and potential water fluxes with soil moisture. The regulation patterns at the two scales will be compared and appropriate models will be identified and parameterized based on the observations.
DE: 1813 Eco-hydrology
DE: 1818 Evapotranspiration
DE: 1836 Hydrological cycles and budgets (1218, 1655)
DE: 1852 Plant uptake
DE: 1866 Soil moisture
SC: Hydrology [H]
MN: 2007 Joint Assembly