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Development and verification of a water and sugar transport model using measured stem diameter variations

Veerle De Schepper UGent and Kathy Steppe UGent (2010) JOURNAL OF EXPERIMENTAL BOTANY. 61(8). p.2083-2099
abstract
In trees, water and sugars are transported by xylem and phloem conduits which are hydraulically linked. A simultaneous study of both flows is interesting, since they concurrently influence important processes such as stomatal regulation and growth. A few mathematical models have already been developed to investigate the influence of both hydraulically coupled flows. However, none of these models were so far tested using real measured field data. In the present study, a comprehensive whole tree model is developed that enables simulation of the stem diameter variations driven by both the water and the sugar transport. Stem diameter variations are calculated as volume changes of both the xylem and the phloem tissue. These volume changes are dependent on: (i) water transport according to the cohesion-tension theory, (ii) sugar transport according to the Münch hypothesis, (iii) loading and unloading of sugars and (iv) irreversible turgor-driven growth. The model considers three main compartments (crown, stem and roots) and is verified by comparison with actual measured stem diameter variations and xylem sap flow rates. These measurements were performed on a young oak (Quercus robur L.) tree in controlled conditions and on an adult beech (Fagus sylvatica L.) tree in a natural forest. A good agreement was found between simulated and measured data. Hence, the model seemed to be a realistic representation of the processes observed in reality. Furthermore, the model is able to simulate several physiological variables which are relatively difficult to measure: phloem turgor, phloem osmotic pressure and the Münch’s counter flow. Simulation of these variables revealed daily dynamics in their behaviour which were mainly induced by transpiration. Some of these dynamics are experimentally confirmed in literature, while others are not.
Please use this url to cite or link to this publication:
author
organization
year
type
journalArticle (original)
publication status
published
subject
keyword
TREE STEMS, PHLOEM, WOODY-PLANTS, TURGOR PRESSURE, MUNCH HYPOTHESIS, RICINUS-COMMUNIS, FLOW CHARACTERISTICS, GROWTH, SAP, XYLEM, Diurnal cycles, Fagus sylvatica L, growth, modelling, Munch hypothesis, phloem translocation, Quercus robur L, sap flow, stem diameter variations, xylem
journal title
JOURNAL OF EXPERIMENTAL BOTANY
J. Exp. Bot.
volume
61
issue
8
pages
2083 - 2099
Web of Science type
Article
Web of Science id
000277987500005
JCR category
PLANT SCIENCES
JCR impact factor
4.818 (2010)
JCR rank
12/185 (2010)
JCR quartile
1 (2010)
ISSN
0022-0957
DOI
10.1093/jxb/erq018
language
English
UGent publication?
yes
classification
A1
copyright statement
I have transferred the copyright for this publication to the publisher
id
843358
handle
http://hdl.handle.net/1854/LU-843358
date created
2010-01-27 16:06:57
date last changed
2011-07-12 11:45:20
@article{843358,
  abstract     = {In trees, water and sugars are transported by xylem and phloem conduits which are hydraulically linked. A simultaneous study of both flows is interesting, since they concurrently influence important processes such as stomatal regulation and growth. A few mathematical models have already been developed to investigate the influence of both hydraulically coupled flows. However, none of these models were so far tested using real measured field data. In the present study, a comprehensive whole tree model is developed that enables simulation of the stem diameter variations driven by both the water and the sugar transport. Stem diameter variations are calculated as volume changes of both the xylem and the phloem tissue. These volume changes are dependent on: (i) water transport according to the cohesion-tension theory, (ii) sugar transport according to the M{\"u}nch hypothesis, (iii) loading and unloading of sugars and (iv) irreversible turgor-driven growth. The model considers three main compartments (crown, stem and roots) and is verified by comparison with actual measured stem diameter variations and xylem sap flow rates. These measurements were performed on a young oak (Quercus robur L.) tree in controlled conditions and on an adult beech (Fagus sylvatica L.) tree in a natural forest. A good agreement was found between simulated and measured data. Hence, the model seemed to be a realistic representation of the processes observed in reality. Furthermore, the model is able to simulate several physiological variables which are relatively difficult to measure: phloem turgor, phloem osmotic pressure and the M{\"u}nch{\textquoteright}s counter flow. Simulation of these variables revealed daily dynamics in their behaviour which were mainly induced by transpiration. Some of these dynamics are experimentally confirmed in literature, while others are not.},
  author       = {De Schepper, Veerle and Steppe, Kathy},
  issn         = {0022-0957},
  journal      = {JOURNAL OF EXPERIMENTAL BOTANY},
  keyword      = {TREE STEMS,PHLOEM,WOODY-PLANTS,TURGOR PRESSURE,MUNCH HYPOTHESIS,RICINUS-COMMUNIS,FLOW CHARACTERISTICS,GROWTH,SAP,XYLEM,Diurnal cycles,Fagus sylvatica L,growth,modelling,Munch hypothesis,phloem translocation,Quercus robur L,sap flow,stem diameter variations,xylem},
  language     = {eng},
  number       = {8},
  pages        = {2083--2099},
  title        = {Development and verification of a water and sugar transport model using measured stem diameter variations},
  url          = {http://dx.doi.org/10.1093/jxb/erq018},
  volume       = {61},
  year         = {2010},
}

Chicago
De Schepper, Veerle, and Kathy Steppe. 2010. “Development and Verification of a Water and Sugar Transport Model Using Measured Stem Diameter Variations.” Journal of Experimental Botany 61 (8): 2083–2099.
APA
De Schepper, V., & Steppe, K. (2010). Development and verification of a water and sugar transport model using measured stem diameter variations. JOURNAL OF EXPERIMENTAL BOTANY, 61(8), 2083–2099.
Vancouver
1.
De Schepper V, Steppe K. Development and verification of a water and sugar transport model using measured stem diameter variations. JOURNAL OF EXPERIMENTAL BOTANY. 2010;61(8):2083–99.
MLA
De Schepper, Veerle, and Kathy Steppe. “Development and Verification of a Water and Sugar Transport Model Using Measured Stem Diameter Variations.” JOURNAL OF EXPERIMENTAL BOTANY 61.8 (2010): 2083–2099. Print.