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Hunan Normal University (2020)

Study on the Mechanical Models for Simulating Transpiration under A Wide Range of Water Condition

刘娜;

Titre : Study on the Mechanical Models for Simulating Transpiration under A Wide Range of Water Condition

Auteur : 刘娜;

Grade : Doctoral Dissertation 2020

Université : Hunan Normal University

Résumé
Plant transpiration depends on environmental conditions(e.g.micrometeorological factors and root zone soil moisture),and soil water deficit is considered the dominant environmental constraint for plant transpiration(and photosynthesis)under water-limited conditions.Buckley,Turnbull and Adams(2013)proposed a simplified process-based model,which is noted as BTA based on the first name of authors,and widely used to estimate plant transpiration and sap flow under stable soil water conditions with simple formulation and less variables(solar radiation(Rs)and vapor pressure deficit(VPD)).However,it fails to simulate transpiration when soil moisture varies widely,as water stress index does not included in the BTA model.In this study,to improve the performance of BTA under a wide range water condition,we modified the BTA model based on soil water potential(ψ),soil water content(θ)and crop water stress index(CWSI),and name them as BTA-ψ,BTA-θand BTA-CWSI,respectively.All the proposed models were examined in simulating transpiration rates at 5 sites under subtropical humid climate zone and Mediterranean climate conditions at both daily and hourly resolutions.The results demonstrated that all proposed models improve the performance of BTA significantly and simulate transpiration effectively under different water conditions,providing useful tools for estimating plant water use at different temporal and spatial scales and under different soil moisture conditions.The detailed results are shown as follows :(1)The parameter Emax(maximum transpiration or sap flow under optimal environmental conditions)in the BTA model was replaced by an equation including soil water potential(ψ)and other two parameters to explicitly represent the dependence of plant transpiration on root-zone moisture conditions.The improved model was denoted as BTA-ψ.The performance of the BTA and BTA-ψmodels were assessed at two sites in Changsha,South China(a subtropical monsoon climate)and one site in Adelaide,South Australia(a Mediterranean climate)with different levels of water stress.The BTA model performed reasonably in estimating daily and hourly transpiration under sufficient water conditions,but it failed during dry periods.Overall,the BTA-ψmodel provided a significant improvement for estimating transpiration under a wide range of soil moisture condition

Mots clés : transpiration estimation; environmental variables; soil water deficit; water stress index; the BTA model;

Présentation (CNKI)

Page publiée le 16 juin 2021, mise à jour le 25 novembre 2021