Journal Article

Tree girdling responses simulated by a water and carbon transport model

Veerle De Schepper and Kathy Steppe

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 108, issue 6, pages 1147-1154
Published in print October 2011 | ISSN: 0305-7364
Published online April 2011 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcr068
Tree girdling responses simulated by a water and carbon transport model

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  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry

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Background and Aims

Girdling, or the removal of a strip of bark around a tree's outer circumference, is often used to study carbon relationships, as it triggers several carbon responses which seem to be interrelated.

Methods

An existing plant model describing water and carbon transport in a tree was used to evaluate the mechanisms behind the girdling responses. Therefore, the (un)loading functions of the original model were adapted and became a function of the phloem turgor pressure.

Key Results

The adapted model successfully simulated the measured changes in stem growth induced by girdling. The model indicated that the key driving variables for the girdling responses were changes in turgor pressure due to local changes in sugar concentrations. Information about the local damage to the phloem system was transferred to the other plant parts (crown and roots) by a change in phloem pressure. After girdling, the loading rate was affected and corresponded to the experimentally observed feedback inhibition. In addition, the unloading rate decreased after girdling and even reversed in some instances. The model enabled continuous simulation of changes in starch content, although a slight underestimation was observed compared with measured values.

Conclusions

For the first time a mechanistic plant model enabled simulation of tree girdling responses, which have thus far only been experimentally observed and fragmentally reported in literature. The close agreement between measured and simulated data confirms the underlying mechanisms introduced in the model.

Keywords: Feedback inhibition; girdling; loading; mechanistic plant modelling; phloem turgor; photosynthesis; Quercus robur L.; stem diameter variations; transport model; unloading

Journal Article.  4929 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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