Leaf hydraulic capacity in ferns, conifers and angiosperms: impacts on photosynthetic maxima

Authors

  • Tim J. Brodribb,

    Corresponding author
    1. Dept. Plant Science, University of Tasmania, GPO 252-55, Hobart 7000, Australia;
    2. Dept. of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, Massachusetts, USA;
      Author for correspondence: Tim J. Brodribb Tel: + 1 61 62261707 Fax: + 1 61 62262698 Email: brodribb@fas.harvard.edu
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  • N. Michele Holbrook,

    1. Dept. of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, Massachusetts, USA;
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  • Maciej A. Zwieniecki,

    1. Facultad de Ciencias Agropecuarias y Ambientales, Universidad de las Americas, Santiago, Chile;
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  • Beatriz Palma

    1. Arnold Arboretum, Harvard University, 16 Divinity Avenue, Cambridge, Massachusetts, USA
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Author for correspondence: Tim J. Brodribb Tel: + 1 61 62261707 Fax: + 1 61 62262698 Email: brodribb@fas.harvard.edu

Summary

  • • The hydraulic plumbing of vascular plant leaves varies considerably between major plant groups both in the spatial organization of veins, as well as their anatomical structure.
  • • Five conifers, three ferns and 12 angiosperm trees were selected from tropical and temperate forests to investigate whether the profound differences in foliar morphology of these groups lead to correspondingly profound differences in leaf hydraulic efficiency.
  • • We found that angiosperm leaves spanned a range of leaf hydraulic conductance from 3.9 to 36 mmol m2 s−1 MPa−1, whereas ferns (5.9–11.4 mmol m−2 s−1 MPa−1) and conifers (1.6–9.0 mmol m−2 s−1 MPa−1) were uniformly less conductive to liquid water. Leaf hydraulic conductance (Kleaf) correlated strongly with stomatal conductance indicating an internal leaf-level regulation of liquid and vapour conductances. Photosynthetic capacity also increased with Kleaf, however, it became saturated at values of Kleaf over 20 mmol m−2 s−1 MPa−1.
  • • The data suggest that vessels in the leaves of the angiosperms studied provide them with the flexibility to produce highly conductive leaves with correspondingly high photosynthetic capacities relative to tracheid-bearing species.

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