%0 Journal Article %1 Verhoef2014Modeling %A Verhoef, Anne %A Egea, Gregorio %D 2014 %J Agricultural and Forest Meteorology %K euporias %P 22--32 %R 10.1016/j.agrformet.2014.02.009 %T Modeling plant transpiration under limited soil water: Comparison of different plant and soil hydraulic parameterizations and preliminary implications for their use in land surface models %U http://dx.doi.org/10.1016/j.agrformet.2014.02.009 %V 191 %X Soil water stress parameterizations for land surface models were compared. Soil moisture content or soil matric potential were the independent variable. Transpiration reduction functions (TRF) based on data from the literature were used. The model that used hydraulic and chemical signaling produced most plausible TRFs. But it was very sensitive to choice of soil hydraulic parameterization and parameters. Accurate estimates of how soil water stress affects plant transpiration are crucial for reliable land surface model (LSM) predictions. Current LSMs generally use a water stress factor, β, dependent on soil moisture content, θ, that ranges linearly between β = 1 for unstressed vegetation and β = 0 when wilting point is reached. This paper explores the feasibility of replacing the current approach with equations that use soil water potential as their independent variable, or with a set of equations that involve hydraulic and chemical signaling, thereby ensuring feedbacks between the entire soil–root–xylem–leaf system. A comparison with the original linear θ-based water stress parameterization, and with its improved curvi-linear version, was conducted. Assessment of model suitability was focused on their ability to simulate the correct (as derived from experimental data) curve shape of relative transpiration versus fraction of transpirable soil water. We used model sensitivity analyses under progressive soil drying conditions, employing two commonly used approaches to calculate water retention and hydraulic conductivity curves. Furthermore, for each of these hydraulic parameterizations we used two different parameter sets, for 3 soil texture types; a total of 12 soil hydraulic permutations. Results showed that the resulting transpiration reduction functions (TRFs) varied considerably among the models. The fact that soil hydraulic conductivity played a major role in the model that involved hydraulic and chemical signaling led to unrealistic values of β, and hence TRF, for many soil hydraulic parameter sets. However, this model is much better equipped to simulate the behavior of different plant species. Based on these findings, we only recommend implementation of this approach into LSMs if great care with choice of soil hydraulic parameters is taken.

@article{Verhoef2014Modeling, abstract = { Soil water stress parameterizations for land surface models were compared. Soil moisture content or soil matric potential were the independent variable. Transpiration reduction functions ({TRF}) based on data from the literature were used. The model that used hydraulic and chemical signaling produced most plausible {TRFs}. But it was very sensitive to choice of soil hydraulic parameterization and parameters. Accurate estimates of how soil water stress affects plant transpiration are crucial for reliable land surface model ({LSM}) predictions. Current {LSMs} generally use a water stress factor, \^{I}², dependent on soil moisture content, \^{I}¸, that ranges linearly between \^{I}² = 1 for unstressed vegetation and \^{I}² = 0 when wilting point is reached. This paper explores the feasibility of replacing the current approach with equations that use soil water potential as their independent variable, or with a set of equations that involve hydraulic and chemical signaling, thereby ensuring feedbacks between the entire soil–root–xylem–leaf system. A comparison with the original linear \^{I}¸-based water stress parameterization, and with its improved curvi-linear version, was conducted. Assessment of model suitability was focused on their ability to simulate the correct (as derived from experimental data) curve shape of relative transpiration versus fraction of transpirable soil water. We used model sensitivity analyses under progressive soil drying conditions, employing two commonly used approaches to calculate water retention and hydraulic conductivity curves. Furthermore, for each of these hydraulic parameterizations we used two different parameter sets, for 3 soil texture types; a total of 12 soil hydraulic permutations. Results showed that the resulting transpiration reduction functions ({TRFs}) varied considerably among the models. The fact that soil hydraulic conductivity played a major role in the model that involved hydraulic and chemical signaling led to unrealistic values of \^{I}², and hence {TRF}, for many soil hydraulic parameter sets. However, this model is much better equipped to simulate the behavior of different plant species. Based on these findings, we only recommend implementation of this approach into {LSMs} if great care with choice of soil hydraulic parameters is taken.}, added-at = {2019-08-14T18:35:35.000+0200}, author = {Verhoef, Anne and Egea, Gregorio}, biburl = {https://www.bibsonomy.org/bibtex/2ed884cb633caca1ba633fa8ea1149b88/karinawilliams}, citeulike-article-id = {13159304}, citeulike-linkout-0 = {http://dx.doi.org/10.1016/j.agrformet.2014.02.009}, doi = {10.1016/j.agrformet.2014.02.009}, interhash = {2499d8fd40e37cdf122a3a5ebb49badb}, intrahash = {ed884cb633caca1ba633fa8ea1149b88}, issn = {01681923}, journal = {Agricultural and Forest Meteorology}, keywords = {euporias}, month = jun, pages = {22--32}, posted-at = {2016-07-04 13:51:39}, priority = {2}, timestamp = {2019-08-14T18:35:35.000+0200}, title = {Modeling plant transpiration under limited soil water: Comparison of different plant and soil hydraulic parameterizations and preliminary implications for their use in land surface models}, url = {http://dx.doi.org/10.1016/j.agrformet.2014.02.009}, volume = 191, year = 2014 }