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Author Verryckt, L.T.; Ellsworth, D.S.; Vicca, S.; Van Langenhove, L.; Peñuelas, J.; Ciais, P.; Posada, J.M.; Stahl, C.; Coste, S.; Courtois, E.A.; Obersteiner, M.; Chave, J.; Janssens, I.A. doi  openurl
  Title Can light-saturated photosynthesis in lowland tropical forests be estimated by one light level? Type Journal Article
  Year 2020 Publication Biotropica Abbreviated Journal Biotropica  
  Volume 52 Issue 6 Pages (down) 1183-1193  
  Keywords canopy architecture; interspecific variation; light intensity; lowland environment; parameter estimation; photon flux density; photosynthesis; saturation; tropical forest; French Guiana  
  Abstract Leaf-level net photosynthesis (An) estimates and associated photosynthetic parameters are crucial for accurately parameterizing photosynthesis models. For tropical forests, such data are poorly available and collected at variable light conditions. To avoid over- or underestimation of modeled photosynthesis, it is critical to know at which photosynthetic photon flux density (PPFD) photosynthesis becomes light-saturated. We studied the dependence of An on PPFD in two tropical forests in French Guiana. We estimated the light saturation range, including the lowest PPFD level at which Asat (An at light saturation) is reached, as well as the PPFD range at which Asat remained unaltered. The light saturation range was derived from photosynthetic light-response curves, and within-canopy and interspecific differences were studied. We observed wide light saturation ranges of An. Light saturation ranges differed among canopy heights, but a PPFD level of 1,000 µmol m−2 s−1 was common across all heights, except for pioneer trees species that did not reach light saturation below 2,000 µmol m−2 s−1. A light intensity of 1,000 µmol m−2 s−1 sufficed for measuring Asat of climax species at our study sites, independent of the species or the canopy height. Because of the wide light saturation ranges, results from studies measuring Asat at higher PPFD levels (for upper canopy leaves up to 1,600 µmol m−2 s−1) are comparable with studies measuring at 1,000 µmol m−2 s−1. © 2020 The Association for Tropical Biology and Conservation  
  Address UMR 5174, Laboratoire Evolution et Diversité Biologique, CNRS, Université Paul Sabatier, Toulouse, France  
  Corporate Author Thesis  
  Publisher Blackwell Publishing Ltd Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 00063606 (Issn) ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number EcoFoG @ webmaster @ Serial 948  
Permanent link to this record
 

 
Author Coste, S.; Roggy, J.C.; Imbert, P.; Born, C.; Bonal, D.; Dreyer, E. openurl 
  Title Leaf photosynthetic traits of 14 tropical rain forest species in relation to leaf nitrogen concentration and shade tolerance Type Journal Article
  Year 2005 Publication Tree Physiology Abbreviated Journal Tree Physiol.  
  Volume 25 Issue 9 Pages (down) 1127-1137  
  Keywords functional diversity; leaf carbon; leaf nitrogen; nitrogen-use efficiency; photosynthetic capacity; tropical rain forest  
  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.  
  Address CNRS Ecol Forets Guyane, INRA, ENGREF,CIRAD, Unite Mixte Rech, Kourou 97387, French Guiana, Email: roggy.j@cirad.fr  
  Corporate Author Thesis  
  Publisher HERON PUBLISHING Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0829-318X ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000231555200005 Approved no  
  Call Number EcoFoG @ eric.marcon @ Serial 230  
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Author Coste, S.; Roggy, J.C.; Garraud, L.; Heuret, P.; Nicolini, E.; Dreyer, E. openurl 
  Title Does ontogeny modulate irradiance-elicited plasticity of leaf traits in saplings of rain-forest tree species? A test with Dicorynia guianensis and Tachigali melinonii (Fabaceae, Caesalpinioideae) Type Journal Article
  Year 2009 Publication Annals of Forest Science Abbreviated Journal Ann. For. Sci.  
  Volume 66 Issue 7 Pages (down) 701-709  
  Keywords plant architecture; phenotypic plasticity; photosynthetic capacity; leaf structure; tropical rain forest  
  Abstract Irradiance elicits a large plasticity in leaf traits, but little is known about the modulation of this plasticity by ontogeny. Interactive effects of relative irradiance and ontogeny were assessed on leaf traits for two tropical rainforest tree species: Dicorynia guianensis Amshoff and Tachigali melinonii (Harms) Barneby (Fabaceae, Caesalpinioideae). Eleven morphological and physiological leaf traits, relative to photosynthetic performance, were measured on saplings at three different architectural development stages (ASD 1, 2 and 3) and used to derive composite traits like photosynthetic N-use efficiency. Measurements were made along a natural irradiance gradient. The effect of ASD was very visible and differed between the two species. For Dicorynia guianensis, only leaf mass-per-area (LMA) significantly increased with ASDs whereas for Tachigali melinonii, almost all traits were affected by ASD: LMA, leaf N content and photosynthetic capacity increased from ASD 1 to ASD 3. Photosynthetic N-use-efficiency was not affected by ASD in any species. Leaf traits were severely modulated by irradiance, whereas the degree of plasticity was very similar among ASDs. Only few interactions were detected between irradiance and ASD, for leaf thickness, carbon content, and the ratio Chl/N in T. melinonii and for photosynthetic capacity in D. guianensis. We conclude that ontogenic development and irradiance-elicited plasticity modulated leaf traits, with almost no interaction, i.e., the degree of irradiance-elicited plasticity was stable across development stages and independent of ontogeny in these two species, at least in the early stages of development assessed here.  
  Address [Dreyer, Erwin] INRA, UMR Ecol & Ecophysiol Forestieres 1137, F-54280 Champenoux, France, Email: dreyer@nancy.inra.fr  
  Corporate Author Thesis  
  Publisher EDP SCIENCES S A Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1286-4560 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000270906600009 Approved no  
  Call Number EcoFoG @ eric.marcon @ Serial 100  
Permanent link to this record
 

 
Author Biwolé, A.B.; Dainou, K.; Fayolle, A.; Hardy, O.J.; Brostaux, Y.; Coste, S.; Delion, S.; Betti, J.L.; Doucet, J.-L. doi  openurl
  Title Light Response of Seedlings of a Central African Timber Tree Species, Lophira alata (Ochnaceae), and the Definition of Light Requirements Type Journal Article
  Year 2015 Publication Biotropica Abbreviated Journal Biotropica  
  Volume 47 Issue 6 Pages (down) 681-688  
  Keywords biomass allocation; Central Africa; light requirement: Lophira alata; population; relative growth rate; seedling growth; timber species; Afrique centrale; allocation de biomasse; besoins en lumière; croissance des semis; bois d'œuvre; Lophira alata; population; taux de croissance relatif  
  Abstract Light is of primary importance in structuring tropical tree communities. Light exposure at seedling and adult stages has been used to characterize the ecological profile of tropical trees, with many implications in forest management and restoration ecology. Most shade-tolerance classification systems have been proposed based on empirical observations in a specific area and thus result in contradictions among categories assigned to a given species. In this study, we aimed to quantify the light requirements for seedling growth of a Central African timber tree, Lophira alata (Ochnaceae), taking into account effects of population origin. In two controlled experiments: a light response experiment and a comparative population experiment, conducted in southwestern Cameroon, using seeds collected from four populations (three from Cameroon and one from Gabon), we examined the quantitative responses to irradiance of seedlings. After 2 years, mortality was very low (<3%), even in extremely low irradiance. Growth and biomass allocation patterns varied in response to light, with intermediate irradiance (24–43%) providing optimal conditions. Light response differed between populations. The Boumba population in the northeastern edge of the species' distribution exhibited the highest light requirements, suggesting a local adaptation. As a result of positive growth at low irradiance and maximum growth at intermediate irradiance, we concluded that L. alata exhibits characteristics of both non-pioneer and pioneer species. Implications of our results to propose an objective way to assign the light requirement for tropical tree species are discussed.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1744-7429 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number EcoFoG @ webmaster @ Serial 648  
Permanent link to this record
 

 
Author Verryckt, L.T.; Van Langenhove, L.; Ciais, P.; Courtois, E.A.; Vicca, S.; Peñuelas, J.; Stahl, C.; Coste, S.; Ellsworth, D.S.; Posada, J.M.; Obersteiner, M.; Chave, J.; Janssens, I.A. doi  openurl
  Title Coping with branch excision when measuring leaf net photosynthetic rates in a lowland tropical forest Type Journal Article
  Year 2020 Publication Biotropica Abbreviated Journal Biotropica  
  Volume 52 Issue 4 Pages (down) 608-615  
  Keywords branch cutting; canopy physiology; French Guiana; gas exchange; photosynthesis; rainforest; stomatal conductance; ecological modeling; environmental conditions; forest canopy; leaf; measurement method; photosynthesis; tree; tropical forest; Gruidae  
  Abstract Measuring leaf gas exchange from canopy leaves is fundamental for our understanding of photosynthesis and for a realistic representation of carbon uptake in vegetation models. Since canopy leaves are often difficult to reach, especially in tropical forests with emergent trees up to 60 m at remote places, canopy access techniques such as canopy cranes or towers have facilitated photosynthetic measurements. These structures are expensive and therefore not very common. As an alternative, branches are often cut to enable leaf gas exchange measurements. The effect of branch excision on leaf gas exchange rates should be minimized and quantified to evaluate possible bias. We compared light-saturated leaf net photosynthetic rates measured on excised and intact branches. We selected branches positioned at three canopy positions, estimated relative to the top of the canopy: upper sunlit foliage, middle canopy foliage, and lower canopy foliage. We studied the variation of the effects of branch excision and transport among branches at these different heights in the canopy. After excision and transport, light-saturated leaf net photosynthetic rates were close to zero for most leaves due to stomatal closure. However, when the branch had acclimated to its new environmental conditions—which took on average 20 min—light-saturated leaf net photosynthetic rates did not significantly differ between the excised and intact branches. We therefore conclude that branch excision does not affect the measurement of light-saturated leaf net photosynthesis, provided that the branch is recut under water and is allowed sufficient time to acclimate to its new environmental conditions. © 2020 The Association for Tropical Biology and Conservation  
  Address UMR 5174 Laboratoire Evolution et Diversité Biologique, Université Paul Sabatier, CNRS, Toulouse, France  
  Corporate Author Thesis  
  Publisher Blackwell Publishing Ltd Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 00063606 (Issn) ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number EcoFoG @ webmaster @ Serial 960  
Permanent link to this record
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