Examination and parameterization of the root water uptake model from stem water potential and sap flow measurements

Authors

  • Yuting Yang,

    Corresponding author
    1. National Centre for Groundwater Research and Training, Adelaide, SA, Australia
    2. School of the Environment, Flinders University, Adelaide, SA, Australia
    • State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing, China
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  • Huade Guan,

    1. National Centre for Groundwater Research and Training, Adelaide, SA, Australia
    2. School of the Environment, Flinders University, Adelaide, SA, Australia
    3. College of Resource and Environment Science, Hunan Normal University, Changsha, China
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  • John L. Hutson,

    1. School of the Environment, Flinders University, Adelaide, SA, Australia
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  • Hailong Wang,

    1. National Centre for Groundwater Research and Training, Adelaide, SA, Australia
    2. School of the Environment, Flinders University, Adelaide, SA, Australia
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  • Caecilia Ewenz,

    1. School of the Environment, Flinders University, Adelaide, SA, Australia
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  • Songhao Shang,

    1. State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing, China
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  • Craig T. Simmons

    1. National Centre for Groundwater Research and Training, Adelaide, SA, Australia
    2. School of the Environment, Flinders University, Adelaide, SA, Australia
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Correspondence to: Yuting Yang, Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China.

E-mail: yyt08@mails.tsinghua.edu.cn

Abstract

A simple field-based method for directly parameterizing root water uptake models is proposed. Stem psychrometers and sap flow meters are used to measure stem water potential and plant transpiration rate continuously and simultaneously. Predawn stem water potential is selected as a surrogate for root zone soil water potential to examine and parameterize the root water uptake–water stress response functions. The method is applied to two drooping sheoak (Allocasuarina verticillata) trees for a period of 80 days, covering both a dry season and a wet season. The results indicate that the S-shape function is more appropriate than the Feddes piecewise linear function for drooping sheoak to represent the effect of soil moisture stress on its root water uptake performance. Besides, the water stress function is found to be not only a function of soil moisture but also dependent of the atmospheric demand. As a result, the water stress function is corrected for the effect of atmospheric conditions. Copyright © 2012 John Wiley & Sons, Ltd.

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