title: Apparent Overinvestment in Leaf Venation Relaxes Leaf Morphological Constraints on Photosynthesis in Arid Habitats.
abstract: Leaf veins supply the mesophyll with water that evaporates when stomata are open to allow CO2uptake for photosynthesis. Theoretical analyses suggest that water is optimally distributed in the mesophyll when the lateral distance between veins (dx) is equal to the distance from these veins to the epidermis (dy), expressed as dx:dy≈ 1. Although this theory is supported by observations of many derived angiosperms, we hypothesize that plants in arid environments may reduce dx:dybelow unity owing to climate-specific functional adaptations of increased leaf thickness and increased vein density. To test our hypothesis, we assembled leaf hydraulic, morphological, and photosynthetic traits of 68 species from the Eucalyptus and Corymbia genera (termed eucalypts) along an aridity gradient in southwestern Australia. We inferred the potential gas-exchange advantage of reducing dxbeyond dyusing a model that links leaf morphology and hydraulics to photosynthesis. Our observations reveal that eucalypts in arid environments have thick amphistomatous leaves with high vein densities, resulting in dx:dyratios that range from 1.6 to 0.15 along the aridity gradient. Our model suggests that, as leaves become thicker, the effect of reducing dxbeyond dyis to offset the reduction in leaf gas exchange that would result from maintaining dx:dyat unity. This apparent overinvestment in leaf venation may be explained from the selective pressure of aridity, under which traits associated with long leaf life span, high hydraulic and thermal capacitances, and high potential rates of leaf water transport confer a competitive advantage.
authors: School of Plant Biology (H.J.d.B., P.L.D., E.W., C.A.P., E.J.V.) and Institute of Agriculture (N.C.T., E.J.V.), University of Western Australia, Crawley 6009, Australia; h.j.deboer@uu.nl erik.veneklaas@uwa.edu.au.|Department of Environmental Sciences, Utrecht University, Utrecht 3584 CS, The Netherlands (H.J.d.B.) h.j.deboer@uu.nl erik.veneklaas@uwa.edu.au.|Max-Planck Institute for Biogeochemistry, Jena 07745, Germany (E.-D.S.); and h.j.deboer@uu.nl erik.veneklaas@uwa.edu.au.|Currency Creek Arboretum, Melrose Park 5039, Australia (D.N.) h.j.deboer@uu.nl erik.veneklaas@uwa.edu.au.
authors: Hugo J
authors: HJ
authors: de Boer
authors: School of Plant Biology (H.J.d.B., P.L.D., E.W., C.A.P., E.J.V.) and Institute of Agriculture (N.C.T., E.J.V.), University of Western Australia, Crawley 6009, Australia.|Department of Environmental Sciences, Utrecht University, Utrecht 3584 CS, The Netherlands (H.J.d.B.).|Max-Planck Institute for Biogeochemistry, Jena 07745, Germany (E.-D.S.); and.|Currency Creek Arboretum, Melrose Park 5039, Australia (D.N.).
authors: Paul L
authors: PL
authors: Drake
authors: School of Plant Biology (H.J.d.B., P.L.D., E.W., C.A.P., E.J.V.) and Institute of Agriculture (N.C.T., E.J.V.), University of Western Australia, Crawley 6009, Australia.|Department of Environmental Sciences, Utrecht University, Utrecht 3584 CS, The Netherlands (H.J.d.B.).|Max-Planck Institute for Biogeochemistry, Jena 07745, Germany (E.-D.S.); and.|Currency Creek Arboretum, Melrose Park 5039, Australia (D.N.).
authors: Erin
authors: E
authors: Wendt
authors: School of Plant Biology (H.J.d.B., P.L.D., E.W., C.A.P., E.J.V.) and Institute of Agriculture (N.C.T., E.J.V.), University of Western Australia, Crawley 6009, Australia.|Department of Environmental Sciences, Utrecht University, Utrecht 3584 CS, The Netherlands (H.J.d.B.).|Max-Planck Institute for Biogeochemistry, Jena 07745, Germany (E.-D.S.); and.|Currency Creek Arboretum, Melrose Park 5039, Australia (D.N.).
authors: Charles A
authors: CA
authors: Price
authors: School of Plant Biology (H.J.d.B., P.L.D., E.W., C.A.P., E.J.V.) and Institute of Agriculture (N.C.T., E.J.V.), University of Western Australia, Crawley 6009, Australia.|Department of Environmental Sciences, Utrecht University, Utrecht 3584 CS, The Netherlands (H.J.d.B.).|Max-Planck Institute for Biogeochemistry, Jena 07745, Germany (E.-D.S.); and.|Currency Creek Arboretum, Melrose Park 5039, Australia (D.N.).
authors: Ernst-Detlef
authors: ED
authors: Schulze
authors: School of Plant Biology (H.J.d.B., P.L.D., E.W., C.A.P., E.J.V.) and Institute of Agriculture (N.C.T., E.J.V.), University of Western Australia, Crawley 6009, Australia.|Department of Environmental Sciences, Utrecht University, Utrecht 3584 CS, The Netherlands (H.J.d.B.).|Max-Planck Institute for Biogeochemistry, Jena 07745, Germany (E.-D.S.); and.|Currency Creek Arboretum, Melrose Park 5039, Australia (D.N.).
authors: Neil C
authors: NC
authors: Turner
authors: School of Plant Biology (H.J.d.B., P.L.D., E.W., C.A.P., E.J.V.) and Institute of Agriculture (N.C.T., E.J.V.), University of Western Australia, Crawley 6009, Australia.|Department of Environmental Sciences, Utrecht University, Utrecht 3584 CS, The Netherlands (H.J.d.B.).|Max-Planck Institute for Biogeochemistry, Jena 07745, Germany (E.-D.S.); and.|Currency Creek Arboretum, Melrose Park 5039, Australia (D.N.).
authors: Dean
authors: D
authors: Nicolle
authors: School of Plant Biology (H.J.d.B., P.L.D., E.W., C.A.P., E.J.V.) and Institute of Agriculture (N.C.T., E.J.V.), University of Western Australia, Crawley 6009, Australia; h.j.deboer@uu.nl erik.veneklaas@uwa.edu.au.|Department of Environmental Sciences, Utrecht University, Utrecht 3584 CS, The Netherlands (H.J.d.B.) h.j.deboer@uu.nl erik.veneklaas@uwa.edu.au.|Max-Planck Institute for Biogeochemistry, Jena 07745, Germany (E.-D.S.); and h.j.deboer@uu.nl erik.veneklaas@uwa.edu.au.|Currency Creek Arboretum, Melrose Park 5039, Australia (D.N.) h.j.deboer@uu.nl erik.veneklaas@uwa.edu.au.
authors: Erik J
authors: 0000-0002-7030-4056
authors: EJ
authors: Veneklaas
mesh_terms: D003889:Desert Climate; D017753:Ecosystem; D005052:Eucalyptus / Q000033:anatomy & histology* / Q000502:physiology*; D005740:Gases / Q000378:metabolism; D016014:Linear Models; D010788:Photosynthesis; D018515:Plant Leaves / Q000033:anatomy & histology* / Q000502:physiology*; D054046:Plant Stomata / Q000033:anatomy & histology; D058526:Plant Vascular Bundle / Q000033:anatomy & histology* / Q000502:physiology; D025341:Principal Component Analysis
chemical_list: D005740:Gases