Leaf trait plasticity in six forest tree species of central Amazonia

Tropical rainforest trees adjust leaf traits during ontogeny to cope with changes in the physical environment and maximize their carbon uptake. The aim of this study was to determine the plasticity index (P-I) of leaf traits in understory and canopy leaves of six Amazonian tree species. In four of the six species the P-I of leaf traits varied within species, and in four of the ten leaf traits assessed, the P-I differed between species. The greatest P-I values were found for stomatal density (D-s) and CO2-saturated photosynthesis, and the lowest ones were found for stomatal size, and leaf thickness. Despite the differences in P-I values within species, the mean P-I was similar in all the six species. As the saplings grow toward the canopy, the strategy to increase carbon uptake involves increasing D-s and leaf nitrogen and reducing stomatal size.