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Keywords:

  • deciduous;
  • evergreen;
  • fibre concentration;
  • leaf mass per area;
  • leaf thickness

Summary

  • 1
    It has been proposed that in longer-living leaves the allocation of biomass to structural components is greater than in shorter-living leaves, leading to a greater leaf mass per area (LMA) and to lower assimilation rates. However, direct evidence in support of this hypothesis is very scarce.
  • 2
    In the present work we investigated the relationships between leaf duration and LMA, leaf thickness and fibre concentrations (cellulose, hemicellulose and lignin) in five oak species, five pine species and three additional tree species, differing in leaf life spans. Correlations among leaf life span and the other leaf traits were obtained both across species (TIPs) and as phylogenetically independent contrasts (PICs).
  • 3
    Leaf thickness and LMA increased steadily with leaf longevity. No relationship was found between leaf longevity and the lignin concentration per unit leaf mass. Evergreen leaves were found to have higher mean concentrations of cellulose and hemicellulose than deciduous ones. However, no relationship was observed between leaf longevity and the concentration of structural carbohydrates across the set of evergreen species, although PIC correlations revealed increases in cellulose with leaf longevity within particular lineages.
  • 4
    Our findings reveal that leaf reinforcement by structural carbohydrates depends on leaf habit (deciduous vs. evergreen) and, within a given lineage, also on leaf longevity. However, among the evergreen species co-occurring in a particular environment, leaf duration may apparently be increased, with no need for increases in the concentration of structural components per unit leaf mass.