title: The anatomical and compositional basis of leaf mass per area.
abstract: Leaf dry mass per unit leaf area (LMA) is a central trait in ecology, but its anatomical and compositional basis has been unclear. An explicit mathematical and physical framework for quantifying the cell and tissue determinants of LMA will enable tests of their influence on species, communities and ecosystems. We present an approach to explaining LMA from the numbers, dimensions and mass densities of leaf cells and tissues, which provided unprecedented explanatory power for 11 broadleaved woody angiosperm species diverse in LMA (33-262 g m-2; R2= 0.94; P < 0.001). Across these diverse species, and in a larger comparison of evergreen vs. deciduous angiosperms, high LMA resulted principally from larger cell sizes, greater major vein allocation, greater numbers of mesophyll cell layers and higher cell mass densities. This explicit approach enables relating leaf anatomy and composition to a wide range of processes in physiological, evolutionary, community and macroecology.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA.
authors.forename: Grace P
authors.initials: GP
authors.lastname: John
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA.
authors.forename: Christine
authors.initials: C
authors.lastname: Scoffoni
authors.affiliation: Plant Breeding Institute, Sydney Institute of Agriculture, The University of Sydney, 12656, Newell Hwy, Narrabri, NSW, 2390, Australia.
authors.forename: Thomas N
authors.initials: TN
authors.lastname: Buckley
authors.affiliation: Área de Ecología, Universidad de Córdoba, Edificio Celestino Mutis, Campus de Rabanales, 14071, Córdoba, Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: Villar
authors.affiliation: Plant Sciences (IBG2), Forschungszentrum Jülich GmbH, D-52425, Jülich, Germany.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Poorter
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA.
authors.forename: Lawren
authors.initials: L
authors.lastname: Sack
mesh_terms: D000071421:Life History Traits; D019684:Magnoliopsida / Q000033:anatomy & histology / Q000502:physiology*; D008954:Models, Biological; D018515:Plant Leaves / Q000033:anatomy & histology / Q000502:physiology*
keywords: 
  SLA
  ; Deciduous; evergreen; functional traits; leaf anatomy; leaf density; leaf economics; leaf thickness; mesophyll; specific leaf area