title: Stronger seasonal adjustment in leaf turgor loss point in lianas than trees in an Amazonian forest.
abstract: Pan-tropically, liana density increases with decreasing rainfall and increasing seasonality. This pattern has led to the hypothesis that lianas display a growth advantage over trees under dry conditions. However, the physiological mechanisms underpinning this hypothesis remain elusive. A key trait influencing leaf and plant drought tolerance is the leaf water potential at turgor loss point (πtlp). πtlpadjusts under drier conditions and this contributes to improved leaf drought tolerance. For co-occurring Amazonian tree (n = 247) and liana (n = 57) individuals measured during the dry and the wet seasons, lianas showed a stronger osmotic adjustment than trees. Liana leaves were less drought-tolerant than trees in the wet season, but reached similar drought tolerances during the dry season. Stronger osmotic adjustment in lianas would contribute to turgor maintenance, a critical prerequisite for carbon uptake and growth, and to the success of lianas relative to trees in growth under drier conditions.
authors.affiliation: Laboratoire EDB, UMR5174, CNRS/Université Paul Sabatier/ENFA, Toulouse, France isabelle.mj.marechaux@gmail.com.|AgroParisTech-ENGREF, Paris, France.
authors.forename: Isabelle
authors.identifier: 0000-0002-5401-0197
authors.initials: I
authors.lastname: Maréchaux
authors.affiliation: Department of Ecology and Evolution, UCLA, Los Angeles, CA, USA.
authors.forename: Megan K
authors.initials: MK
authors.lastname: Bartlett
authors.affiliation: Laboratoire EDB, UMR5174, CNRS/Université Paul Sabatier/ENFA, Toulouse, France.
authors.forename: Amaia
authors.initials: A
authors.lastname: Iribar
authors.affiliation: Department of Ecology and Evolution, UCLA, Los Angeles, CA, USA.
authors.forename: Lawren
authors.initials: L
authors.lastname: Sack
authors.affiliation: Laboratoire EDB, UMR5174, CNRS/Université Paul Sabatier/ENFA, Toulouse, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Chave
mesh_terms: D000222:Adaptation, Physiological; D055864:Droughts; D005616:French Guiana; D009997:Osmotic Pressure; D018515:Plant Leaves / Q000502:physiology*; D012621:Seasons; D014197:Trees / Q000502:physiology*; D014329:Tropical Climate; D014867:Water / Q000502:physiology*
chemical_list: D014867:Water
keywords: drought tolerance; functional traits; leaf water potential; lianas; plasticity; wilting point