Reconciling species-level vs plastic responses of evergreen leaf structure to light gradients: shade leaves punch above their weight
Article first published online: 23 FEB 2010
© The Authors (2010). Journal compilation © New Phytologist Trust (2010)
Volume 186, Issue 2, pages 429–438, April 2010
How to Cite
Lusk, C. H., Onoda, Y., Kooyman, R. and Gutiérrez-Girón, A. (2010), Reconciling species-level vs plastic responses of evergreen leaf structure to light gradients: shade leaves punch above their weight. New Phytologist, 186: 429–438. doi: 10.1111/j.1469-8137.2010.03202.x
- Issue published online: 25 MAR 2010
- Article first published online: 23 FEB 2010
- Received: 9 October 2009, Accepted: 17 December 2009
- countergradient variation;
- leaf economics spectrum;
- leaf mass per area;
- leaf resistance to fracture;
- neutral detergent fibre;
- subtropical rainforest
- •When grown in a common light environment, the leaves of shade-tolerant evergreen trees have a larger leaf mass per unit area (LMA) than their light-demanding counterparts, associated with differences in lifespan. Yet plastic responses of LMA run counter to this pattern: shade leaves have smaller LMA than sun leaves, despite often living longer.
- •We measured LMA and cell wall content, and conducted punch and shear tests, on sun and shade leaves of 13 rainforest evergreens of differing shade tolerance, in order to understand adaptation vs plastic responses of leaf structure and biomechanics to shade.
- •Species shade tolerance and leaf mechanical properties correlated better with cell wall mass per unit area than with LMA. Growth light environment had less effect on leaf mechanics than on LMA: shade leaves had, on average, 40% lower LMA than sun leaves, but differences in work-to-shear, and especially force-to-punch, were smaller. This was associated with a slightly larger cell wall fraction in shade leaves.
- •The persistence of shade leaves might reflect unattractiveness to herbivores because they yield smaller benefits (cell contents per area) per unit fracture force than sun leaves. In forest trees, cell wall fraction and force-to-punch are more robust correlates of species light requirements than LMA.