title: An empirical study of the wound effect on sap flux density measured with thermal dissipation probes.
abstract: The insertion of thermal dissipation (TD) sensors on tree stems for sap flux density (SFD) measurements can lead to SFD underestimations due to a wound formation close to the drill hole. However, the wound effect has not been assessed experimentally for this method yet. Here, we propose an empirical approach to investigate the effect of the wound healing on measured sap flux with TD probes. The approach was performed for both, diffuse-porous (Fagus sylvatica (Linnaeus)) and ring-porous (Quercus petraea (Lieblein)) species. Thermal dissipation probes were installed on different dates along the growing season to document the effects of the dynamic wound formation. The trees were cut in autumn and additional sensors were installed in the cut stems, therefore, without potential effects of wound development. A range of water pressures was applied to the stem segments and SFDs were simultaneously measured by TD sensors as well as gravimetrically in the laboratory. The formation of wounds around sensors installed in living tree stems led to underestimation of SFD by 21.4 ± 3 and 47.5 ± 3.8% in beech and oak, respectively. The differences between SFD underestimations of diffuse-porous beech and ring-porous oak were, however, not statistically significant. Sensors with 5-, 11- and 22-week-old wounds also showed no significant differences, which implies that the influence of wound formation on SFD estimates was completed within the first few weeks after perforation. These results were confirmed by time courses of SFD measurements in the field. Field SFD values decreased immediately after sensor installation and reached stable values after ~2 weeks with similar underestimations to the ones observed in the laboratory. We therefore propose a feasible approach to correct directly field observations of SFD for potential underestimations due to the wound effect.
authors: Department Computational Hydrosystems, UFZ-Helmholtz Centre for Environmental Research, Permoserstraße 15, 04318 Leipzig, Germany.|Institute for Geological Sciences, Friedrich-Schiller-University Jena, Burgweg 11, 07749 Jena, Germany.
authors: Andreas
authors: A
authors: Wiedemann
authors: Department Computational Hydrosystems, UFZ-Helmholtz Centre for Environmental Research, Permoserstraße 15, 04318 Leipzig, Germany smaranon@ugr.es.|Institute for Geological Sciences, Friedrich-Schiller-University Jena, Burgweg 11, 07749 Jena, Germany.|Department of Applied Physics, University of Granada, Av. Fuentenueva s/n, E-18071 Granada, Spain.
authors: Sara
authors: S
authors: Marañón-Jiménez
authors: Department Computational Hydrosystems, UFZ-Helmholtz Centre for Environmental Research, Permoserstraße 15, 04318 Leipzig, Germany.
authors: Corinna
authors: C
authors: Rebmann
authors: Thünen Institute of Climate Smart Agriculture, Bundesallee 50, 38116 Braunschweig, Germany.
authors: Mathias
authors: M
authors: Herbst
authors: Department Computational Hydrosystems, UFZ-Helmholtz Centre for Environmental Research, Permoserstraße 15, 04318 Leipzig, Germany.
authors: Matthias
authors: M
authors: Cuntz
mesh_terms: D015374:Biosensing Techniques; D029964:Fagus; D065928:Forests; D006358:Hot Temperature; D010935:Plant Diseases; D018526:Plant Transpiration; D029963:Quercus; D014197:Trees
keywords: European beech; Fagus sylvatica; Quercus petraea; heat transfer; sap flow; sap flow underestimations; sap velocity; sessile oak; wound healing reaction