title: An empirical method that separates irreversible stem radial growth from bark water content changes in trees: theory and case studies.
abstract: Substantial uncertainty surrounds our knowledge of tree stem growth, with some of the most basic questions, such as when stem radial growth occurs through the daily cycle, still unanswered. We employed high-resolution point dendrometers, sap flow sensors, and developed theory and statistical approaches, to devise a novel method separating irreversible radial growth from elastic tension-driven and elastic osmotically driven changes in bark water content. We tested this method using data from five case study species. Experimental manipulations, namely a field irrigation experiment on Scots pine and a stem girdling experiment on red forest gum trees, were used to validate the theory. Time courses of stem radial growth following irrigation and stem girdling were consistent with a-priori predictions. Patterns of stem radial growth varied across case studies, with growth occurring during the day and/or night, consistent with the available literature. Importantly, our approach provides a valuable alternative to existing methods, as it can be approximated by a simple empirical interpolation routine that derives irreversible radial growth using standard regression techniques. Our novel method provides an improved understanding of the relative source-sink carbon dynamics of tree stems at a sub-daily time scale.
authors.affiliation: School of GeoSciences, University of Edinburgh, Edinburgh, EH9 3JN, UK.|CREAF, Cerdanyola del Vallès, Barcelona, 08193, Spain.|ICREA, Pg. Lluís Companys 23, Barcelona, 08010, Spain.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Mencuccini
authors.affiliation: Department of Physics, University of Helsinki, Helsinki, 00014, Finland.
authors.forename: Yann
authors.initials: Y
authors.lastname: Salmon
authors.affiliation: CSIRO Land and Water, Hobart, Tas., Australia.
authors.forename: Patrick
authors.initials: P
authors.lastname: Mitchell
authors.affiliation: Department of Forest Sciences, University of Helsinki, Helsinki, 00014, Finland.
authors.forename: Teemu
authors.initials: T
authors.lastname: Hölttä
authors.affiliation: Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, 2753, Australia.
authors.forename: Brendan
authors.initials: B
authors.lastname: Choat
authors.affiliation: School of GeoSciences, University of Edinburgh, Edinburgh, EH9 3JN, UK.|Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia.
authors.forename: Patrick
authors.initials: P
authors.lastname: Meir
authors.affiliation: CSIRO Land and Water, Hobart, Tas., Australia.
authors.forename: Anthony
authors.initials: A
authors.lastname: O'Grady
authors.affiliation: Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, 2753, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Tissue
authors.affiliation: Swiss Federal Institute for Forest, Snow and Landscape Research, (WSL), Birmensdorf, 8903, Switzerland.
authors.forename: Roman
authors.initials: R
authors.lastname: Zweifel
authors.affiliation: Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
authors.forename: Sanna
authors.initials: S
authors.lastname: Sevanto
authors.affiliation: Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, 2753, Australia.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Pfautsch
mesh_terms: D057914:Agricultural Irrigation; D001315:Australia; D005052:Eucalyptus / Q000502:physiology; D008954:Models, Biological; D009995:Osmosis; D024301:Plant Bark / Q000737:chemistry*; D018547:Plant Stems / Q000254:growth & development* / Q000502:physiology; D013557:Switzerland; D014197:Trees / Q000254:growth & development* / Q000502:physiology; D014867:Water / Q000032:analysis*
chemical_list: D014867:Water
keywords: bark water use; hydraulic capacitance; plant water potential; stem dendrometry