title: Monitoring of Freezing Dynamics in Trees: A Simple Phase Shift Causes Complexity.
abstract: During winter, trees have to cope with harsh conditions, including extreme freeze-thaw stress. This study focused on ice nucleation and propagation, related water shifts and xylem cavitation, as well as cell damage and was based on in situ monitoring of xylem (thermocouples) and surface temperatures (infrared imaging), ultrasonic emissions, and dendrometer analysis. Field experiments during late winter onPicea abiesgrowing at the alpine timberline revealed three distinct freezing patterns: (1) from the top of the tree toward the base, (2) from thin branches toward the main stem's top and base, and (3) from the base toward the top. Infrared imaging showed freezing within branches from their base toward distal parts. Such complex freezing causes dynamic and heterogenous patterns in water potential and probably in cavitation. This study highlights the interaction between environmental conditions upon freezing and thawing and demonstrates the enormous complexity of freezing processes in trees. Diameter shrinkage, which indicated water fluxes within the stem, and acoustic emission analysis, which indicated cavitation events near the ice front upon freezing, were both related to minimum temperature and, upon thawing, related to vapor pressure deficit and soil temperature. These complex patterns, emphasizing the common mechanisms between frost and drought stress, shed new light on winter tree physiology.
authors.affiliation: Department of Botany and Department of Ecology, University of Innsbruck, A-6020 Innsbruck, Austria (G.C., M.N., G.L., A.L., U.T., S.M.); guillaume.charrier@inra.fr.|Bordeaux Science Agro, Institut des Sciences de la Vigne et du Vin, Ecophysiologie et Génomique Fonctionnelle de la Vigne, Unité Mixte de Recherche 1287, F-33140 Villenave d'Ornon, France (G.C.); guillaume.charrier@inra.fr.|BIOGECO, Institut National de la Recherche Agronomique, Université Bordeaux, 33610 Cestas, France (G.C.); guillaume.charrier@inra.fr.|Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, New South Wales 2753, Australia (M.N.); guillaume.charrier@inra.fr.|Université Clermont Auvergne, Institut National de la Recherche Agronomique, PIAF, F-6300 Clermont-Ferrand, France (K.C.-V., T.A.); and guillaume.charrier@inra.fr.|Institute for Alpine Environment, European Academy Bozen, 39100 Bozen/Bolzano, Italy (U.T.) guillaume.charrier@inra.fr.
authors.forename: Guillaume
authors.identifier: 0000-0001-8722-8822
authors.initials: G
authors.lastname: Charrier
authors.affiliation: Department of Botany and Department of Ecology, University of Innsbruck, A-6020 Innsbruck, Austria (G.C., M.N., G.L., A.L., U.T., S.M.).|Bordeaux Science Agro, Institut des Sciences de la Vigne et du Vin, Ecophysiologie et Génomique Fonctionnelle de la Vigne, Unité Mixte de Recherche 1287, F-33140 Villenave d'Ornon, France (G.C.).|BIOGECO, Institut National de la Recherche Agronomique, Université Bordeaux, 33610 Cestas, France (G.C.).|Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, New South Wales 2753, Australia (M.N.).|Université Clermont Auvergne, Institut National de la Recherche Agronomique, PIAF, F-6300 Clermont-Ferrand, France (K.C.-V., T.A.); and.|Institute for Alpine Environment, European Academy Bozen, 39100 Bozen/Bolzano, Italy (U.T.).
authors.forename: Markus
authors.identifier: 0000-0001-5374-3113
authors.initials: M
authors.lastname: Nolf
authors.affiliation: Department of Botany and Department of Ecology, University of Innsbruck, A-6020 Innsbruck, Austria (G.C., M.N., G.L., A.L., U.T., S.M.).|Bordeaux Science Agro, Institut des Sciences de la Vigne et du Vin, Ecophysiologie et Génomique Fonctionnelle de la Vigne, Unité Mixte de Recherche 1287, F-33140 Villenave d'Ornon, France (G.C.).|BIOGECO, Institut National de la Recherche Agronomique, Université Bordeaux, 33610 Cestas, France (G.C.).|Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, New South Wales 2753, Australia (M.N.).|Université Clermont Auvergne, Institut National de la Recherche Agronomique, PIAF, F-6300 Clermont-Ferrand, France (K.C.-V., T.A.); and.|Institute for Alpine Environment, European Academy Bozen, 39100 Bozen/Bolzano, Italy (U.T.).
authors.forename: Georg
authors.identifier: 0000-0001-6639-3386
authors.initials: G
authors.lastname: Leitinger
authors.affiliation: Department of Botany and Department of Ecology, University of Innsbruck, A-6020 Innsbruck, Austria (G.C., M.N., G.L., A.L., U.T., S.M.).|Bordeaux Science Agro, Institut des Sciences de la Vigne et du Vin, Ecophysiologie et Génomique Fonctionnelle de la Vigne, Unité Mixte de Recherche 1287, F-33140 Villenave d'Ornon, France (G.C.).|BIOGECO, Institut National de la Recherche Agronomique, Université Bordeaux, 33610 Cestas, France (G.C.).|Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, New South Wales 2753, Australia (M.N.).|Université Clermont Auvergne, Institut National de la Recherche Agronomique, PIAF, F-6300 Clermont-Ferrand, France (K.C.-V., T.A.); and.|Institute for Alpine Environment, European Academy Bozen, 39100 Bozen/Bolzano, Italy (U.T.).
authors.forename: Katline
authors.initials: K
authors.lastname: Charra-Vaskou
authors.affiliation: Department of Botany and Department of Ecology, University of Innsbruck, A-6020 Innsbruck, Austria (G.C., M.N., G.L., A.L., U.T., S.M.).|Bordeaux Science Agro, Institut des Sciences de la Vigne et du Vin, Ecophysiologie et Génomique Fonctionnelle de la Vigne, Unité Mixte de Recherche 1287, F-33140 Villenave d'Ornon, France (G.C.).|BIOGECO, Institut National de la Recherche Agronomique, Université Bordeaux, 33610 Cestas, France (G.C.).|Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, New South Wales 2753, Australia (M.N.).|Université Clermont Auvergne, Institut National de la Recherche Agronomique, PIAF, F-6300 Clermont-Ferrand, France (K.C.-V., T.A.); and.|Institute for Alpine Environment, European Academy Bozen, 39100 Bozen/Bolzano, Italy (U.T.).
authors.forename: Adriano
authors.identifier: 0000-0001-7839-4941
authors.initials: A
authors.lastname: Losso
authors.affiliation: Department of Botany and Department of Ecology, University of Innsbruck, A-6020 Innsbruck, Austria (G.C., M.N., G.L., A.L., U.T., S.M.).|Bordeaux Science Agro, Institut des Sciences de la Vigne et du Vin, Ecophysiologie et Génomique Fonctionnelle de la Vigne, Unité Mixte de Recherche 1287, F-33140 Villenave d'Ornon, France (G.C.).|BIOGECO, Institut National de la Recherche Agronomique, Université Bordeaux, 33610 Cestas, France (G.C.).|Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, New South Wales 2753, Australia (M.N.).|Université Clermont Auvergne, Institut National de la Recherche Agronomique, PIAF, F-6300 Clermont-Ferrand, France (K.C.-V., T.A.); and.|Institute for Alpine Environment, European Academy Bozen, 39100 Bozen/Bolzano, Italy (U.T.).
authors.forename: Ulrike
authors.identifier: 0000-0002-0195-7459
authors.initials: U
authors.lastname: Tappeiner
authors.affiliation: Department of Botany and Department of Ecology, University of Innsbruck, A-6020 Innsbruck, Austria (G.C., M.N., G.L., A.L., U.T., S.M.).|Bordeaux Science Agro, Institut des Sciences de la Vigne et du Vin, Ecophysiologie et Génomique Fonctionnelle de la Vigne, Unité Mixte de Recherche 1287, F-33140 Villenave d'Ornon, France (G.C.).|BIOGECO, Institut National de la Recherche Agronomique, Université Bordeaux, 33610 Cestas, France (G.C.).|Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, New South Wales 2753, Australia (M.N.).|Université Clermont Auvergne, Institut National de la Recherche Agronomique, PIAF, F-6300 Clermont-Ferrand, France (K.C.-V., T.A.); and.|Institute for Alpine Environment, European Academy Bozen, 39100 Bozen/Bolzano, Italy (U.T.).
authors.forename: Thierry
authors.identifier: 0000-0001-6919-3531
authors.initials: T
authors.lastname: Améglio
authors.affiliation: Department of Botany and Department of Ecology, University of Innsbruck, A-6020 Innsbruck, Austria (G.C., M.N., G.L., A.L., U.T., S.M.).|Bordeaux Science Agro, Institut des Sciences de la Vigne et du Vin, Ecophysiologie et Génomique Fonctionnelle de la Vigne, Unité Mixte de Recherche 1287, F-33140 Villenave d'Ornon, France (G.C.).|BIOGECO, Institut National de la Recherche Agronomique, Université Bordeaux, 33610 Cestas, France (G.C.).|Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, New South Wales 2753, Australia (M.N.).|Université Clermont Auvergne, Institut National de la Recherche Agronomique, PIAF, F-6300 Clermont-Ferrand, France (K.C.-V., T.A.); and.|Institute for Alpine Environment, European Academy Bozen, 39100 Bozen/Bolzano, Italy (U.T.).
authors.forename: Stefan
authors.identifier: 0000-0002-3319-4396
authors.initials: S
authors.lastname: Mayr
mesh_terms: D001692:Biological Transport / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology; D017753:Ecosystem; D005615:Freezing; D007053:Ice; D028222:Picea / Q000033:anatomy & histology / Q000502:physiology*; D018547:Plant Stems / Q000033:anatomy & histology / Q000502:physiology*; D012621:Seasons; D013312:Stress, Physiological; D013696:Temperature; D014197:Trees / Q000033:anatomy & histology / Q000502:physiology*; D014465:Ultrasonics / Q000379:methods; D014867:Water / Q000378:metabolism; D052584:Xylem / Q000033:anatomy & histology / Q000502:physiology*
chemical_list: D007053:Ice; D014867:Water