Using Sap Flow Data to Parameterize the Feddes Water Stress Model for Norway Spruce

Rabbel, Inken; Bogena, Heye; Neuwirth, Burkhard; Diekkrüger, Bernd

doi:10.3390/w10030279

Cited by 19 publications

(7 citation statements)

References 75 publications

(104 reference statements)

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“…This means, that the vast majority of isotope based RWU studies is based on graphic or statistical methods, which allow a description of observations but abstain from offering physically-based models, which could be used to predict the reaction of RWU to changing environmental conditions. Lv (2014), Rabbel et al (2018) and Brinkmann et al (2018) have modelled RWU of trees with implementations of a Feddes-style RWU model described by Feddes et al (1976) and Jarvis (1989) as implemented within the soil hydrological model HYDRUS-1D (Šimůnek et al, 2008). Even though the Feddes RWU model was originally developed to model water uptake of agricultural crops, the above listed applications demonstrated that Feddes RWU models are also suited to simulate RWU of mature trees.…”

Section: Water Uptake and Tree Isotope Modellingmentioning

confidence: 99%

Temporal dynamics of tree xylem water isotopes: In-situ monitoring and modelling

Seeger¹,

Weiler²

2021

Preprint

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Abstract. We developed a setup for a fully automated, high frequency in-situ monitoring system of the stable water isotopes Deuterium and 18O in soil water and tree xylem. The setup was tested for 12 weeks within an isotopic labelling experiment during a large artificial sprinkling experiment including three mature European beech (Fagus sylvatica) trees. Our setup allowed for one measurement every 12–20 minutes, enabling us to obtain about seven measurements per day for each of our 15 in-situ probes in the soil and tree xylem. While the labelling induced an abrupt step pulse in the soil water isotopic signature, it took seven to ten days until the isotopic signatures at the trees' stem bases reached their peak label concentrations and it took about 14 days until the isotopic signatures at 8 m stem height levelled off around the same values. During the experiment, we observed the effects of several rain events and dry periods on the xylem water isotopic signatures, which fluctuated between the measured isotopic signatures observed in the upper and lower soil horizons. In order to explain our observations, we combined an already existing root water uptake (RWU) model with a newly developed approach to simulate the propagation of isotopic signatures from the root tips to the stem base and further up along the stem. The key to a proper simulation of the observed short term dynamics of xylem water isotopes, was accounting for sap flow velocities and the flow path length distribution within the root and stem xylem. Our modelling framework allowed us to identify parameter values that relate to root depth, horizontal root distribution and wilting point. The insights gained from this study can help to improve the representation of stable water isotopes in trees within ecohydrological models and the prediction of transit time distribution and water age of transpiration fluxes.

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Section: Water Uptake and Tree Isotope Modellingmentioning

confidence: 99%

Temporal dynamics of tree xylem water isotopes: In-situ monitoring and modelling

Seeger¹,

Weiler²

2021

Preprint

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“…Sap flow instruments are widely used for the estimation of whole-plant water use and transpiration [3][4][5]. The accuracy of sap flow measurements and the upscaling of these to the whole-plant water use relies on the knowledge of species-specific physiological characteristics, as well as on information of radial and circumferential patterns of sap velocity [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Tree Water Dynamics in a Semi-Arid, Pinus brutia Forest

Eliades

Bruggeman

Djuma

et al. 2018

Water

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This study aims to examine interactions between tree characteristics, sap flow, and environmental variables in an open Pinus brutia (Ten.) forest with shallow soil. We examined radial and azimuthal variations of sap flux density (Jp), and also investigated the occurrence of hydraulic redistribution mechanisms, quantified nocturnal tree transpiration, and analyzed the total water use of P. brutia trees during a three-year period. Sap flow and soil moisture sensors were installed onto and around eight trees, situated in the foothills of the Troodos Mountains, Cyprus. Radial observations showed a linear decrease of sap flux densities with increasing sapwood depth. Azimuthal differences were found to be statistically insignificant. Reverse sap flow was observed during low vapor pressure deficit (VPD) and negative air temperatures. Nocturnal sap flow was about 18% of the total sap flow. Rainfall was 507 mm in 2015, 359 mm in 2016, and 220 mm in 2017. Transpiration was 53%, 30%, and 75%, respectively, of the rainfall in those years, and was affected by the distribution of the rainfall. The trees showed an immediate response to rainfall events, but also exploited the fractured bedrock. The transpiration and soil moisture levels over the three hydrologically contrasting years showed that P. brutia is well-adapted to semi-arid Mediterranean conditions.

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“…Until recently, measurements of δ xyl and isotopic compositions of soil water (δ soil ) usually required the laborious extraction of the respective waters. Scholander pressure chambers (Scholander et al, 1965) can be used to extract xylem water from branches (Rennenberg et al, 1996;Magh et al, 2020). Another common xylem water extraction method is cryogenic vacuum extraction (Dawson and Ehleringer, 1991;Orlowski et al, 2013;Newberry et al, 2017), which is also commonly used for soil pore water extraction (Dalton, 1988).…”

Section: Measurement Of Soil and Xylem Water Isotopesmentioning

confidence: 99%

Temporal dynamics of tree xylem water isotopes: in situ monitoring and modeling

Seeger

Weiler

2021

Biogeosciences

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Abstract. We developed a setup for a fully automated, high-frequency in situ monitoring system of the stable water isotope deuterium and 18O in soil water and tree xylem. The setup was tested for 12 weeks within an isotopic labeling experiment during a large artificial sprinkling experiment including three mature European beech (Fagus sylvatica) trees. Our setup allowed for one measurement every 12–20 min, enabling us to obtain about seven measurements per day for each of our 15 in situ probes in the soil and tree xylem. While the labeling induced an abrupt step pulse in the soil water isotopic signature, it took 7 to 10 d until the isotopic signatures at the trees' stem bases reached their peak label concentrations and it took about 14 d until the isotopic signatures at 8 m stem height leveled off around the same values. During the experiment, we observed the effects of several rain events and dry periods on the xylem water isotopic signatures, which fluctuated between the measured isotopic signatures observed in the upper and lower soil horizons. In order to explain our observations, we combined an already existing root water uptake (RWU) model with a newly developed approach to simulate the propagation of isotopic signatures from the root tips to the stem base and further up along the stem. The key to a proper simulation of the observed short-term dynamics of xylem water isotopes was accounting for sap flow velocities and the flow path length distribution within the root and stem xylem. Our modeling framework allowed us to identify parameter values that relate to root depth, horizontal root distribution and wilting point. The insights gained from this study can help to improve the representation of stable water isotopes in trees within ecohydrological models and the prediction of transit time distribution and water age of transpiration fluxes.

show abstract

Using Sap Flow Data to Parameterize the Feddes Water Stress Model for Norway Spruce

Cited by 19 publications

References 75 publications

Temporal dynamics of tree xylem water isotopes: In-situ monitoring and modelling

Temporal dynamics of tree xylem water isotopes: In-situ monitoring and modelling

Tree Water Dynamics in a Semi-Arid, Pinus brutia Forest

Temporal dynamics of tree xylem water isotopes: in situ monitoring and modeling

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