Wood density is likely to shape plant functioning through its impact on carbon gain, biomechanical and hydraulic safety and defence. In support of this, Herault et?al. (2011) found that wood density was a significant predictor of ontogenetic variation in diameter GR among 50 rain forest tree species in French Guiana. As expected, the study described herein provided evidence of a negative relationship between LMA plasticity and degree of specialization along the light gradient (rs?=??0.68, P?<?0.01), despite the exclusion of gap and understorey specialists from our subset of species. Species with a low degree of specialization (occurring <a href="http://www.selleckchem.com/TGF-beta.html
">find more with an even frequency over the light gradient) exhibited greater LMA plasticity than species more specialized at one end of the light gradient. This underlines the adaptive value of LMA response to light level. One hypothesis underlying this adaptive response is that interception is optimized in low-light through a greater leaf area per unit leaf biomass; under high-light conditions, photosynthesis rates are increased by greater leaf biomass for a given unit of leaf area. This has been corroborated by comparisons between sun and shade leaves (Onoda, Schieving & Anten 2008); the results showed sun leaves to contain larger amounts of palisade mesophyll Sotrastaurin
associated with a higher photosynthetic capacity (Niinemets 1997). Overall, this finding suggests that LMA plasticity might enable species to enlarge their light niche breadth. In the past, the literature on LMA and other leaf trait plasticity in tropical trees mainly focused on the correlation with light niche optimum. These studies (Valladares et?al. 2000; Rozendaal, Hurtado & Poorter 2006; Lusk et?al. 2010) did not result in a clear consensus but postulated that plasticity is greater in pioneer species as these experience more pronounced and more predictable light variations. This lack of consistency might stem from differences between studies in terms of ontogenetic stage (plasticity is likely to depend on ontogenetic stage, see (Thomas & Winner 2002), observational conditions (field versus controlled environment) and methods of plasticity quantification. These conflicting selleckchem
results may also suggest that there is no significant relationship between LMA plasticity and light niche optimum. Our findings point towards phenotypic plasticity in functional traits that warrant further investigation in relation to niche breadth. The present study also supported the working hypothesis that leaf plasticity in response to light level is higher for species subjected to a major ontogenetic change in light availability, reflected by high adult stature (Table?3).