Leaf hydraulic architecture correlates with regeneration irradiance in tropical rainforest trees

Authors

  • Lawren Sack,

    Corresponding author
    1. Department of Botany, University of Hawai‘i at Mānoa, 3190 Maile Way, Honolulu, HI 96822, USA;
    2. Smithsonian Tropical Research Institute, Apartado Postal 2072, Balboa, Ancon, Republic of Panama;
    3. Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA;
    4. Arnold Arboretum of Harvard University, 125 Arborway, Jamaica Plain, MA 02130, USA;
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  • Melvin T. Tyree,

    1. Smithsonian Tropical Research Institute, Apartado Postal 2072, Balboa, Ancon, Republic of Panama;
    2. USDA Forest Service, 705 Spear Street, PO Box 968, Burlington, VT 05402, USA
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  • N. Michele Holbrook

    1. Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA;
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Author for correspondence: Lawren Sack Tel: +1 808 956 9389 Fax: +1 808 956 3923 Email: Lsack@hawaii.edu

Summary

  • • The leaf hydraulic conductance (Kleaf) is a major determinant of plant water transport capacity. Here, we measured Kleaf, and its basis in the resistances of leaf components, for fully illuminated leaves of five tree species that regenerate in deep shade, and five that regenerate in gaps or clearings, in Panamanian lowland tropical rainforest. We also determined coordination with stomatal characters and leaf mass per area.
  • • Kleaf varied 10-fold across species, and was 3-fold higher in sun- than in shade-establishing species. On average, 12% of leaf hydraulic resistance (= 1/Kleaf) was located in the petiole, 25% in the major veins, 25% in the minor veins, and 39% outside the xylem. Sun-establishing species had a higher proportion of leaf resistance in the xylem. Across species, component resistances correlated linearly with total leaf resistance.
  • • Kleaf correlated tightly with indices of stomatal pore area, indicating a coordination of liquid- and vapor-phase conductances shifted relative to that of temperate woody species.
  • • Leaf hydraulic properties are integrally linked in the complex of traits that define differences in water use and carbon economy across habitats and vegetation zones.

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