title: Variable hydraulic resistances and their impact on plant drought response modelling.
abstract: Plant drought responses are still not fully understood. Improved knowledge on drought responses is, however, crucial to better predict their impact on individual plant and ecosystem functioning. Mechanistic models in combination with plant measurements are promising for obtaining information on plant water status and can assist us in understanding the effect of limiting soil water availability and drought stress. While existing models are reliable under sufficient soil water availability, they generally fail under dry conditions as not all appropriate mechanisms seem yet to have been implemented. We therefore aimed at identifying mechanisms underlying plant drought responses, and in particular investigated the behaviour of hydraulic resistances encountered in the soil and xylem for grapevine (Vitis vinifera L.) and oak (Quercus robur L.). A variable hydraulic soil-to-stem resistance was necessary to describe plant drought responses. In addition, implementation of a variable soil-to-stem hydraulic resistance enabled us to generate an in situ soil-to-stem vulnerability curve, which might be an alternative to the conventionally used vulnerability curves. Furthermore, a daily recalibration of the model revealed a drought-induced increase in radial hydraulic resistance between xylem and elastic living tissues. Accurate information on plant hydraulic resistances and simulation of plant drought responses can foster important discussions regarding the functioning of plants and ecosystems during droughts.
authors.affiliation: Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 Ghent, Belgium.
authors.forename: Annelies
authors.initials: A
authors.lastname: Baert
authors.affiliation: Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 Ghent, Belgium.
authors.forename: Veerle
authors.initials: V
authors.lastname: De Schepper
authors.affiliation: Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 Ghent, Belgium Kathy.Steppe@UGent.be.
authors.forename: Kathy
authors.initials: K
authors.lastname: Steppe
mesh_terms: D000222:Adaptation, Physiological; D055864:Droughts; D008954:Models, Biological; D018547:Plant Stems / Q000502:physiology; D018526:Plant Transpiration; D029963:Quercus / Q000502:physiology*; D012987:Soil; D013312:Stress, Physiological; D027843:Vitis / Q000502:physiology*; D014867:Water / Q000502:physiology*; D052584:Xylem / Q000502:physiology*
chemical_list: D012987:Soil; D014867:Water
keywords: drought-induced hydraulic failure; grapevine; hydraulic conductance; oak; point dendrometers; sap flow; soil conductance; stem diameter variations; stem water potential; water deficit