Leaves at low versus high rainfall: coordination of structure, lifespan and physiology

Authors

  • Ian J. Wright,

    Corresponding author
    1. Department of Biological Sciences, Macquarie University, Sydney 2109, Australia
      Author for correspondence: I. J. Wright Tel: +61 2 9850 8194 Fax: +61 2 9850 8245 Email: iwright@rna.bio.mq.edu.au
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  • Mark Westoby

    1. Department of Biological Sciences, Macquarie University, Sydney 2109, Australia
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Author for correspondence: I. J. Wright Tel: +61 2 9850 8194 Fax: +61 2 9850 8245 Email: iwright@rna.bio.mq.edu.au

Summary

  • • Across species, leaf lifespan (LL) tends to be correlated with leaf mass per area (LMA). Previously we found that Australian perennial species from low-rainfall sites had c . 40% shorter LL at a given LMA than high-rainfall species.
  • • Here we relate indices of leaf strength (work to shear, W shear , and tissue toughness) to LL and LMA across the same suite of species. W shear is the work required to cut a leaf with a blade; W shear divided by leaf thickness gives tissue toughness.
  • • Low- and high-rainfall species did not differ in their LL at a given W shear , but dry-site species had lower W shear at a given LMA, leading to the observed LL – LMA shift with rainfall. These patterns were driven by 50% lower tissue toughness in dry-site species.
  • • The lower toughness was linked with high leaf N concentration, which is known to enhance water conservation during photosynthesis in low-rainfall species. Our results suggest that a significant cost of this strategy is reduced LL for a given investment in leaf tissue (LMA).

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