How cellulose-based leaf toughness and lamina density contribute to long leaf lifespans of shade-tolerant species
Article first published online: 18 JUN 2012
© 2012 The Authors. New Phytologist © 2012 New Phytologist Trust
Volume 195, Issue 3, pages 640–652, August 2012
How to Cite
Kitajima, K., Llorens, A.-M., Stefanescu, C., Timchenko, M. V., Lucas, P. W. and Wright, S. J. (2012), How cellulose-based leaf toughness and lamina density contribute to long leaf lifespans of shade-tolerant species. New Phytologist, 195: 640–652. doi: 10.1111/j.1469-8137.2012.04203.x
- Issue published online: 9 JUL 2012
- Article first published online: 18 JUN 2012
- Received: 31 January 2012, Accepted: 29 April 2012
- anti-herbivory defence;
- lamina density;
- leaf lifespan;
- leaf toughness;
- seedling survival;
- shade tolerance
- •Cell wall fibre and lamina density may interactively affect leaf toughness and leaf lifespan. Here, we tested this with seedlings of 24 neotropical tree species differing in shade tolerance and leaf lifespan under standardized field conditions (140–867 d in gaps; longer in shade). We quantified toughness with a cutting test, explicitly seeking a mechanistic linkage to fibre.
- •Lamina density, but not fracture toughness, exhibited a plastic response to gaps vs shade, while neither trait was affected by leaf age. Toughness corrected for lamina density, a recently recognized indicator of material strength per unit mass, was linearly correlated with cellulose content per unit dry mass.
- •Leaf lifespan was positively correlated with cellulose and toughness in shade-tolerant species but only weakly in gap-dependent species. Leaf lifespan was uncorrelated with lamina thickness, phenolics and tannin concentrations. In path analysis including all species, leaf lifespan was directly enhanced by density and toughness, and indirectly by cellulose via its effect on toughness. Different suites of leaf traits were correlated with early seedling survival in gaps vs shade.
- •In conclusion, cellulose and lamina density jointly enhance leaf fracture toughness, and these carbon-based physical traits, rather than phenolic-based defence, explain species differences in herbivory, leaf lifespan and shade survival.