The successional status of tropical rainforest tree species is associated with differences in leaf carbon isotope discrimination and functional traits

Abstract

-We characterised the among species variability in leaf gas exchange and morphological traits under controlled conditions of seedlings of 22 tropical rainforest canopy species to understand the origin of the variability in leaf carbon isotope discrimination (∆) among species with different growth and dynamic characteristics (successional gradient). Our results first suggest that these species pursue a consistent strategy in terms of ∆ throughout their ontogeny (juveniles grown here versus canopy adult trees from the natural forest). Second, leaf ∆ was negatively correlated with WUE and N, and positively correlated with g s , but among species differences in ∆ were mainly explained by differences in WUE. Finally, species belonging to different successional groups display distinct leaf functional and morphological traits. We confirmed that fast growing early successional species maximise carbon assimilation with high stomatal conductance. In contrast, fast and slow growing late successional species are both characterised by low carbon assimilation values, but by distinct stomatal conductance and leaf morphological features. Along the successional gradient, these differences result in much lower ∆ for the intermediate species (i.e. fast growing late successional) as compared to the two other groups.13 C / functional diversity / leaf gas exchange / species grouping / tropical rainforest Résumé -Le statut successionnel des espèces de la forêt tropicale humide est associé à des différences de discrimination isotopique du carbone et de traits fonctionnels foliaires. Nous avons caractérisé la variabilité interspécifique des échanges gazeux et des traits morphologiques foliaires en conditions environnementales contrôlées de jeunes plants de 22 espèces d'arbres de la canopée en forêt tropicale humide afin de comprendre l'origine de la variabilité de la discrimination isotopique du carbone foliaire (∆) observée entre ces espèces présentant des caractéristiques de croissance et de dynamique distinctes (groupes successionnels). Nous montrons premièrement que les espèces tropicales possèdent une stratégie très conservée de ∆ au cours de leur ontogénie (juvéniles élevés ici versus arbres adultes de la canopée en forêt naturelle). Deuxièmement, ∆ était négativement corrélée à WUE et N, et positivement à g s , mais les différences de ∆ entre espèces sont principalement expliquées par des différences de WUE. Enfin, nous montrons que les espèces appartenant à des groupes successionnels distincts présentent des traits fonctionnels et morphologiques foliaires distincts. Nous confirmons que les espèces à croissance rapide qui s'installent en premier au cours de la succession écologique (FE) maximisent A avec de fortes conductances stomatiques. Les espèces climax (qui s'installent en second dans la succession écologique), à croissance rapide (FL) ou à croissance faible (SL), présentent des valeurs de A identiques, mais des valeurs de g s ainsi que des caractéristiques morphologiques foliaires distinctes. Dans la succession éc...

Genetic variation for growth, morphological, and physiological traits in a wild population of the Neotropical shade­tolerant rainforest tree Sextonia rubra (Mez) van der Werff (Lauraceae)

“…A negative correlation is usually found at the interspecific level between photosynthesis traits and LMA (Bonal et al 2007;Coste et al 2005;Wright et al 2004), indicating trade-offs among between light and carbon acquisition, on one end, and allocation and growth, on the other end. In contrast, this correlation was positive at the intraspecific level in our study, suggesting that these trade-offs do not hold at the intraspecific level.…”

“…Associations of traits have been largely described in the literature, at the global scale (Wright et al 2004) or at the tropical rainforest scale (Baraloto et al 2005;Bonal et al 2007;Santiago and Wright 2007). A negative correlation is usually found at the interspecific level between photosynthesis traits and LMA (Bonal et al 2007;Coste et al 2005;Wright et al 2004), indicating trade-offs among between light and carbon acquisition, on one end, and allocation and growth, on the other end.…”

Variability and grouping of leaf traits in multi-species reforestation (Leyte, Philippines)

“…However, a strong inverse relationship was found when dipertocarp species were analysed as a sub-set, with SLA as predictor variable. A study on successional classification of tropical rainforest species in French Guiana suggests a classification of late successional species into fast-growing and slow-growing ones (Bonal et al, 2007). Our data implies that H. plagata and S. polysperma have leaf traits that characterize slow-growing species, whereas H. malibato and S. contorta may be grouped as fast-growing, late successional species with low g s and high SLA, with P. malaanonan intermediate.…”

Linking rainforest ecophysiology and microclimate through fusion of airborne LiDAR and hyperspectral imagery

“…13 C is typically thought to represent changes in foliar water use efficiency (WUE) resulting from differences in water availability (Seibt et al 2008) or structural differences in the leaf (Bonal et al 2007). Variation in foliar d 13 C due to differences in atmospheric isotopic composition (i.e., increased respired versus atmospheric CO 2 ) would be unlikely to have an effect v www.esajournals.org higher than 3-5 m (Ometto et al 2002) and leaf height was a non-significant predictor of variation in foliar d 13 C. Our d 13 C values were similar to those reported in the Amazon (Ometto et al 2006).…”