title: Physiological and structural tradeoffs underlying the leaf economics spectrum.
abstract: The leaf economics spectrum (LES) represents a suite of intercorrelated leaf traits concerning construction costs per unit leaf area, nutrient concentrations, and rates of carbon fixation and tissue turnover. Although broad trade-offs among leaf structural and physiological traits have been demonstrated, we still do not have a comprehensive view of the fundamental constraints underlying the LES trade-offs. Here, we investigated physiological and structural mechanisms underpinning the LES by analysing a novel data compilation incorporating rarely considered traits such as the dry mass fraction in cell walls, nitrogen allocation, mesophyll CO2diffusion and associated anatomical traits for hundreds of species covering major growth forms. The analysis demonstrates that cell wall constituents are major components of leaf dry mass (18-70%), especially in leaves with high leaf mass per unit area (LMA) and long lifespan. A greater fraction of leaf mass in cell walls is typically associated with a lower fraction of leaf nitrogen (N) invested in photosynthetic proteins; and lower within-leaf CO2diffusion rates, as a result of thicker mesophyll cell walls. The costs associated with greater investments in cell walls underpin the LES: long leaf lifespans are achieved via higher LMA and in turn by higher cell wall mass fraction, but this inevitably reduces the efficiency of photosynthesis.
authors.affiliation: Graduate School of Agriculture, Kyoto University, Kyoto, 606-8502, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Onoda
authors.affiliation: Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia.
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Wright
authors.affiliation: Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, 0200, Australia.
authors.forename: John R
authors.initials: JR
authors.lastname: Evans
authors.affiliation: Graduate School of Life Sciences, Tohoku University, Aoba, Sendai, 980-8578, Japan.
authors.forename: Kouki
authors.initials: K
authors.lastname: Hikosaka
authors.affiliation: Graduate School of Agriculture, Kyoto University, Kyoto, 606-8502, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Kitajima
authors.affiliation: Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Tartu, 51014, Estonia.
authors.forename: Ülo
authors.initials: Ü
authors.lastname: Niinemets
authors.affiliation: Plant Sciences (IBG-2), Forschungszentrum Jülich GmbH, D-52425, Jülich, Germany.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Poorter
authors.affiliation: Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Tartu, 51014, Estonia.
authors.forename: Tiina
authors.initials: T
authors.lastname: Tosens
authors.affiliation: Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia.
authors.forename: Mark
authors.initials: M
authors.lastname: Westoby
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism; D002473:Cell Wall / Q000737:chemistry / Q000378:metabolism; D004058:Diffusion; D058503:Mesophyll Cells / Q000737:chemistry / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*; D018515:Plant Leaves / Q000033:anatomy & histology* / Q000502:physiology*; D010940:Plant Proteins / Q000378:metabolism; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D002245:Carbon Dioxide; D012273:Ribulose-Bisphosphate Carboxylase; D009584:Nitrogen
keywords: anatomy; biodiversity; cell walls; leaf economics spectrum; mesophyll conductance; nitrogen allocation; photosynthesis