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Examination and parameterization of the root water uptake model from stem water potential and sap flow measurements
Author(s) -
Yang Yuting,
Guan Huade,
Hutson John L.,
Wang Hailong,
Ewenz Caecilia,
Shang Songhao,
Simmons Craig T.
Publication year - 2012
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.9406
Subject(s) - transpiration , environmental science , water content , soil water , water potential , water flow , hydrology (agriculture) , soil science , water stress , moisture , atmospheric sciences , horticulture , botany , chemistry , biology , photosynthesis , geology , geotechnical engineering , organic chemistry
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.