Leaf photosynthetic traits of 14 tropical rain forest species in relation to leaf nitrogen concentration and shade tolerance

Abstract

Variability of leaf traits related to photosynthesis was assessed in seedlings from 14 tree species growing in the tropical rain forest of French Guiana. Leaf photosynthetic capacity (maximum rate of carboxylation and maximum rate of electron transport) was estimated by fitting a biochemical model of photosynthesis to response curves of net CO2 assimilation rate versus intercellular CO2 mole fraction. Leaf morphology described by leaf mass per unit leaf area (LMA), density and thickness, as well as area- and mass-based nitrogen (N) and carbon (C) concentrations, were recorded on the same leaves. Large interspecific variability was detected in photosynthetic capacity as well as in leaf structure and leaf N and C concentrations. No correlation was found between leaf thickness and density. The correlations between area- and mass-based leaf N concentration and photosynthetic capacity were poor. Conversely, the species differed greatly in relative N allocation to carboxylation and bioenergetics. Principal component analysis (PCA) revealed that, of the recorded traits, only the computed fraction of total leaf N invested in photosynthesis was tightly correlated to photosynthetic capacity. We also used PCA to test to what extent species with similar shade tolerances displayed converging leaf traits related to photosynthesis. No clear-cut ranking could be detected among the shade-tolerant groups, as confirmed by a one-way ANOVA. We conclude that the large interspecific diversity in photosynthetic capacity was mostly explained by differences in the relative allocation of N to photosynthesis and not by leaf N concentration, and that leaf traits related to photosynthetic capacity did not discriminate shade-tolerance ranking of these tropical tree species.

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

“…In contrast, comparisons within the late successional group (fast growing late successional, FL, versus slow growing late successional, SL) are more scarce. Whereas no significant differences in photosynthetic capacities among these two groups were observed in a common garden experiment [10], higher values of A and N were found in FL species (defined as "intermediate") as compared to SL ones in an in situ experiment on saplings in BCI, Panama [15]. Furthermore, sunlit leaf carbon isotope discrimination (∆) of adult trees was lower in FL species as compared to SL and FE species in different tree communities in French Guiana [7,26], underlying an original non-linear distribution (modal distribution) of this trait along the successional gradient.…”

“…Gas exchange measurements were conducted on two leaves per plant under the following nonlimiting environmental conditions [10]: [CO2] = 360 ppm; PAR = 670 ± 20 µmol m −2 s −1 ; vapour pressure deficit = 1.2 ± 0.4 kPa; air temperature = 30.0 ± 2.1˚C. Equations of Caemmerer and Farquhar [8] were used to calculate net carbon assimilation rate on a leaf area (A, µmol m −2 s −1 ) or mass (A m , mmol g −1 s −2 ) basis, stomatal conductance for water vapour (g s , mol m −2 s −1 ) and intrinsic water-use efficiency (WUE = A/g s ).…”

Características funcionais de folhas de sol e sombra de espécies arbóreas em uma mata de galeria no Distrito Federal, Brasil

“…Os resultados aqui apresentados mostram que a relação entre a assimilação de CO 2 e nutrientes foliares, como N e P, foram signifi cativas quando esta foi expressa com base na massa seca (A massa ) e somente para as folhas de sombra, de modo que essas relações são dependentes das condições ambientais. Investigações anteriores em outros tipos fl orestais mostram que essas relações tendem a ser variáveis e modifi cadas devido a diferentes características ambientais encontradas nos diversos ecossistemas fl orestais da região neotropical e da Oceania, onde geralmente há uma fraca, porém signifi cativa, relação entre A massa , SLA e os nutrientes foliares, como nitrogênio e fósforo (Wright et al 2001;Prior et al 2004;Wright et al 2004;Coste et al 2005).…”

“…Para fl orestas da bacia Amazônica, diversos autores têm relatado diferenças na concentração de nitrogênio foliar (Bonal et al 2000, Coste et al 2005, Rozendaal et al 2006), e que as diferenças entre folhas de sol e sombra também estariam relacionadas a diferenças no investimento em diferentes estruturas foliares e a AFE. Markesteijn et al (2007) comparando seus resultados com fl orestas mais secas e mais úmidas, sugeriram que a resposta de folhas de sol e sombra pode ser variável de acordo com interação entre disponibilidade hídrica e intensidade luminosa dos diferentes tipos fl orestais.…”

A trait database for Guianan rain forest trees permits intra- and inter-specific contrasts

“…Nitrogen: Isotopic signature (δ 15 N) and leaf nitrogen concentration in various forest sites [35][36][37][38] Carbon: δ13C values and leaf carbon concentration at several sites [4] Photosynthesis-related ecophysiological parameters measured in glasshouse [8] Biomechanics…”