Extrait de : Contribution à l'étude des bois de la Guyane Française (entre p. 104 et p. 105)
Résumé : (Vouacapoua Americana) C. transversale et C. tangentielle
Siècle(s) traité(s) : 20
Droits : Domaine public
Permalien : http://www.manioc.org/images/GAD120260133
GAD120260133

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Questions: Several studies have described aggregated spatial patterns in tropical tree species. This study investigates aggregate dynamics of Vouacapoua americana (Aublet), a climax species whose spatial pattern is not simply related to light and soil conditions or to its short seed dispersal range. Location: Two rain forest sites: Nouragues and Paracou, in the Guiana Shield. Methods: We described the spatial pattern of tree locations and spatial autocorrelation of tree diameters, using statistics derived from Ripley's K. We particularly used methods to define analysis subplots according to local density or local mean diameter. We investigated relationships between spatial distributions of adults and saplings. Results: At both sites, populations of Vouacapoua demonstrated several nested levels of aggregation. Tree diameters were spatially autocorrelated, revealing the existence of clusters with similar diameters. In the largest aggregates, tree diameters declined from the centre to the edge. Regeneration was aggregated and occurred mainly at cluster edges and around rare isolated trees, and sapling densities and basal area of adults were negatively correlated. We show that long-distance dispersal events are rare. Conclusions: Environmental factors and seed dispersal only explain part of the observed spatial patterns. We provide two main hypotheses about Vouacapoua population dynamics. First, the lack of regeneration in aggregate centres results in the ageing of existing aggregates. We suggest that this lack of recruitment close to mature trees is due to a Janzen-Connell effect. However, aggregates can continue to grow along colonization fronts. Second, long-distance dispersal events allow the formation of new clusters and play a crucial role in the colonization process. We investigate aggregate dynamics of Vouacapoua americana (Aublet) whose spatial pattern is not simply related to environmental conditions or to its seed dispersal. Regeneration does not occur in centers of aggregate of adults. We suggest that rare long-distance dispersal events and density-dependence predation of seeds and seedlings play a crucial role in formation of new clusters and structuration of larger aggregates.
ISSN: 1100-9233

hal-01502642
https://hal-agroparistech.archives-ouvertes.fr/hal-01502642
DOI : 10.1111/jvs.12080

Éditeur(s) : HAL CCSD
Résumé :   Diplôme : DEA
il s'agit d'un type de produit dont les métadonnées ne correspondent pas aux métadonnées attendues dans les autres types de produit : DISSERTATION
L'étude de la répartition géographique de la diversité génétique résultant de l'histoire des populations apparaît comme fondamentale pour la conservation des espèces. Ainsi, la mise en évidence des relations phylo-géographiques au court du Quaternaire récent, au sein d'une espèce modèle Vouacapoua americana (Caesalpiniaceae), en Guyane française apporte des informations importantes sur la dynamique des populations naturelles. Dans cette étude les loci trn Q-trn S et trn Sa-trn fM sont utilisés afin de déterminer l'histoire évolutive des populations issues des refuges forestiers tropicaux. Le but principal est l'obtention des séquences après amplification PCR. L'analyse de ces séquences chez cinq populations testées a permis de mettre en évidence leur caractère hypervariable, ainsi que des régions présentant des motifs conservés répétés plusieurs fois. Les constructions phylogéographiques obtenues à partir de celles-ci accentuent la régionalisation des différents chlorotypes, existant en Guyane pour cette espèce, mise en évidence au cours de travaux précédents. Ainsi, les informations apportées par cette approche apparaissent comme complémentaires aux résultats obtenus par d'autres techniques d'analyse moléculaire.
https://hal.archives-ouvertes.fr/hal-01189224

hal-01189224
https://hal.archives-ouvertes.fr/hal-01189224
PRODINRA : 16622

Éditeur(s) : HAL CCSD Ecole nationale du génie rural
Résumé :  
Les bois tropicaux, et en particulier les bois de Guyane, témoignent de la biodiversité des forêts denses humides. Les atouts et contraintes liés à cette diversité sont présentés ainsi que la façon objective de classer les espèces ou essences par rapport à des critères de qualité. La variabilité de la qualité des bois est illustrée à travers quelques exemples : la qualité des arbres sur pied, la qualité non constante de l'Angélique (Dicorynia guianensis), les troncs cannelés du Wacapou (Vouacapoua americana), les différences entre deux espèces d'Eperua Spp.. La conclusion porte sur la petite filière-bois guyanaise, ses difficultés et les enjeux à relever.
ISSN: 0035-2829

hal-01031808
https://hal.archives-ouvertes.fr/hal-01031808

Éditeur(s) : HAL CCSD Elsevier
Résumé : Over-exploitation and fragmentation are serious problems for tropical forests. Most sustainable forest management practices avoid clear-cuts and apply selective logging systems focused on a few commercial species. We applied a simulation model to estimate the impact of such selective logging scenarios on the genetic diversity and demography of four tropical tree species from French Guiana. The simulations used data on genetic and demographic composition, growth, phenology and pollen and seed dispersal obtained for Dicorynia guianensis, Sextonia rubra, Symphonia globulifera and Vouacapoua americana at the experimental site in Paracou. Whereas Symphonia globulifera serves as a model for a species with low logging pressure, the other three species represent the most exploited tree species in French Guiana. In simulations with moderate logging, typical for French Guiana, with large cutting diameter (>60 cm diameter) and long cutting cycles (65 years), the two species V. americana and Sextonia rubra were not able to recover their initial stock at the end of the rotation period, with a large decrease in the number of individuals and in basal area. Under a more intensive logging system (cutting diameter >45 cm diameter, cutting cycles of 30 years) that is common practice in the Brazilian Amazon, only Symphonia globulifera showed no negative impact. Generally, the differences between the genetic parameters in the control scenarios without logging and the logging scenarios were surprisingly small. The main reasons for this were the overlapping of generations and the effective dispersal ability of gene vectors in all species, which guarantee relative homogeneity of the genetic structure in different age classes. Nevertheless, decreasing the population size by logging reduced the number of genotypes and caused higher genetic distances between the original population and the population at the end of the logging cycles. Sensitivity analysis showed that genetic changes in the logging scenarios were principally determined by the growth, densities and cutting diameter of each species, and only to a very small extent by the reproductive system including factors such as pollen and seed dispersal and flowering phenology
ISSN: 0006-3207

hal-01032050
https://hal.archives-ouvertes.fr/hal-01032050
DOI : 10.1016/j.biocon.2006.02.014

Éditeur(s) : HAL CCSD Wiley
Résumé :  
Drier periods from the late Pleistocene and early Holocene have been hypothesized to have caused the disappearance of various rainforest species over large geographical areas in South America and restricted the extant populations to mesic sites. Subsequent improvement in climatic conditions has been associated with recolonization. Changes in population size associated with these extinction-recolonization events should have affected genetic diversity within species. However, these historical hypotheses and their genetic consequences have rarely been tested in South America. Here, we examine the diversity of the chloroplast and nuclear genomes in a Neotropical rainforest tree species, Vouacapoua americana (Leguminosae, Caesalpinioideae) in French Guiana. The chloroplast diversity was analyzed using a polymerase chain reaction-restriction fragment length polymorphism method (six pairs of primers) in 29 populations distributed over most of French Guiana, and a subset of 17 populations was also analyzed at nine polymorphic microsatellite loci. To determine whether this species has experienced extinction-recolonization, we sampled populations in areas supposedly not or only slightly affected by climatic changes, where the populations would not have experienced frequent extinction, and in areas that appear to have been recently recolonized. In the putatively recolonized areas, we found patches of several thousands of hectares homogeneous for chloroplast variation that can be interpreted as the effect of recolonization processes from several geographical origins. In addition, we observed that, for both chloroplast and nuclear genomes, the populations in newly recolonized areas exhibited a significantly smaller allelic richness than others. Controlling for geographic distance, we also detected a significant correlation between chloroplast and nuclear population differentiation. This result indicates a cytonuclear disequilibrium that can be interpreted as a historical signal of a genetic divergence between fragmented populations. In conclusion, the spatial genetic structure of contemporary V. americana populations shows evidence that this species has experienced large extinction-recolonization events, which were possibly caused by past climatic change.
ISSN: 0014-3820

hal-01032194
https://hal.archives-ouvertes.fr/hal-01032194
DOI : 10.1111/j.0014-3820.2003.tb01517.x

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The study of decay resistance in wood is of interest for wood end-users but also for the global carbon balance since wood biodegradation is a key driver of forest ecosystem functioning through its impacts on carbon and nutrient cycling. We studied the density and wood extractive contents in order to understand decay resistance against soil microflora after 90 days exposure of sapwood and heartwood from three Neotropical wood species known for their decay resistance: Bocoa prouacensis, Vouacapoua americana, Inga alba. Decay resistance was correlated with density more than wood extractive content. The results highlighted different decay resistance strategies. In B. prouacensis, both sapwood and heartwood were highly resistant due to the high density and high content of antifungal wood extractives. In V. americana heartwood, decay resistance was due to the high synergistic-acting wood extractive content. Conversely, with the least dense wood species I. alba, we found that decay resistance was due to the antifungal wood extractives synthesized early in the sapwood. In conclusion, we showed that the three wood species with the same level of heartwood decay resistance performance had different decay resistance strategies according to the anatomic and defensive wood traits.
ISSN: 0964-8305

hal-01321162
https://hal.archives-ouvertes.fr/hal-01321162
https://hal.archives-ouvertes.fr/hal-01321162/document
https://hal.archives-ouvertes.fr/hal-01321162/file/Art_Amusant_al_Diversity_decay_resistance_strategies_Int.Biodet.Biodegr._2014.pdf
DOI : 10.1016/j.ibiod.2014.06.012

Éditeur(s) : HAL CCSD Wiley
Résumé :  
The chloroplast genome has been widely used to describe genetic diversity in plant species. Its maternal inheritance in numerous angiosperm species and low mutation rate are suitable characters when inferring historical events such as possible recolonization routes. Here we have studied chloroplast DNA variation using PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) with seven pairs of primers and four restriction enzymes in 14 populations of Vouacapoua americana (Caesalpiniaceae) a neotropical tree sampled throughout French Guiana. Population diversity (Hs), total gene diversity (Ht) and differentiation among populations (GST) were estimated using Nei's method as 0.09, 0.87 and 0.89, respectively. This is consistent with the limited gene flow associated with synzoochory in this species. The genetic structure observed in the north of French Guiana suggests that historical events such as contractions and recent recolonizations have had a large impact on the distribution of genetic diversity in this species.
ISSN: 0962-1083

hal-01032176
https://hal.archives-ouvertes.fr/hal-01032176
DOI : 10.1046/j.1365-294x.2000.01027.x

Éditeur(s) : HAL CCSD Wiley
Résumé : 1- We examined among- and within-species effects of seed mass for seedling establishment from seed to 5 years of age in a field experiment at Paracou, French Guiana. 2- Six seeds of each of eight species were weighed and planted into each of 120 plots (1 m2) throughout closed-canopy forest along 12 100-m transects in 1998. 3- We described the microhabitat of each planting site using principal components derived from measurements of light availability, soil moisture, carbon and nitrogen content, and soil phosphorus availability. Although both survival and relative growth rate (RGR) increased with increasing light availability, no other microhabitat variable significantly affected seedling performance. Nor did the magnitude of microhabitat effects on survival or RGR differ among species. 4- Larger-seeded species were more likely to survive from germination to 1 year as well as from 1 to 5 years of age. RGR for seedling height during the first year post-germination was not related to seed mass, but smaller-seeded species did grow slightly faster thereafter. Path analyses revealed that correlations between seed mass and performance were explained in part because larger seeds produced larger initial seedlings, which tended to survive better but grow more slowly. 5- We also analysed within-species effects of seed mass for the larger-seeded Eperua grandiflora and Vouacapoua americana (both Caesalpiniaceae). Larger seeds produced larger seedlings in both species, but larger seeds survived better only for Eperua. Larger seedlings grew more slowly in both species, but did not offset the early (Eperua) and later (Vouacapoua) positive direct effects of seed mass on RGR that may represent contrasting strategies for reserve deployment. 6- Our results demonstrate that seed size influences performance within and among species in part because of indirect effects of initial seedling size. However, we suggest that traits tightly correlated with seed mass at the species level, such as specific leaf area, leaf longevity and photosynthetic capacity, may also contribute to interspecific performance differences.
ISSN: 0022-0477

hal-01031089
https://hal.archives-ouvertes.fr/hal-01031089
DOI : 10.1111/j.1365-2745.2005.01041.x

Éditeur(s) : HAL CCSD
Résumé :   Diplôme : DEA
il s'agit d'un type de produit dont les métadonnées ne correspondent pas aux métadonnées attendues dans les autres types de produit : DISSERTATION
Links between architectural stages of development (ASD), photosynthetic capacities and leaf characteristics in Tachigali melinonii (Caesalpiniaceae) were investigated in the tropical forest of French Guiana. Three ASD were sampled under three light conditions to elucidate the impact of ASD- and light-related changes on photosynthetic functional traits. Photosynthetic parameters (maximum rate in RubisCO carboxylation (Vcmax) and maximum rate of electron transport (Jmax) were estimated by adjusting a biochemical model (Farquhar et al., 1980) to response curves of CO2 assimilation rate to intercellular CO2 concentration, under saturated light. In addition, N and C foliar concentrations were analysed and N allocations to the carboxylation and bioenergetic processus of photosynthesis were calculated using the model of Niinemets and Tenhunen (1997). The variations in ecophysiological parameters observed were due to leaf anatomical and structural changes instead of changes in photosynthetic components, suggesting adjustments to light conditions. Tachigali melinonii thus appears to display morphological and anatomical plasticity at different ASDs and under different light conditions.
Une espèce forestière de Guyane Française, Tachigali melinonii (Caesalipiniaceae), a été choisie afin de regarder la variation des traits fonctionnels relatifs à la photosynthèse en fonction de la disponibilité en lumière et en fonction de son stade de développement architectural. Du fait du tempérament de l'espèce vis-à-vis de la lumière de type «struggling gambler» (ombrage nécessaire aux jeunes stades puis développement en pleine lumière), trois stades clefs de développement parmi la séquence de différenciation de l'espèce ainsi que trois environnements lumineux ont été choisis. Les capacités photosynthétiques foliaires ont été estimées à partir de l'ajustement de paramètres du modèle biochimique de photosynthèse foliaire (Farquhar et al. 1980) sur des courbes de réponses de l'assimilation de CO² (A) à des concentrations intracellulaires en CO² (Ci) croissantes, en condition de lumière saturante. La vitesse maximale de carboxylation Vcmax et le flux maximal d'électrons photosynthétiques Jmax ont ainsi été estimés et ensuite reliés aux caractéristiques structurales foliaires, notamment la concentration en azote, en carbone ainsi qu'avec la densité et l’épaisseur. Les fractions d'azote allouées aux processus photosynthétiques de carboxylation et de bioénergétique ont été calculées. Des variations, dues à un effet du stade de développement sur les paramètres étudiés ainsi qu’à un effet de la quantité de lumière disponible, ont été constatées. Ces variations sont surtout liées à des ajustements anatomiques et structuraux foliaires et non à des modifications de l’appareil photosynthétique. Tachigali melinonii semble donc modifier ses caractéristiques structurales foliaires en fonction de son stade de développement, ce qui suppose un contrôle ontogénique partiel, et en fonction de la disponibilité en lumière.
https://hal.archives-ouvertes.fr/hal-01189520

hal-01189520
https://hal.archives-ouvertes.fr/hal-01189520
PRODINRA : 44951

Éditeur(s) : HAL CCSD
Résumé : Diffusion du document : INRA Antilles-Guyane, UMR ECOFOG, 97387 Kourou, Guyane (France) Diplôme : DEA
il s'agit d'un type de produit dont les métadonnées ne correspondent pas aux métadonnées attendues dans les autres types de produit : DISSERTATION
Nous avons étudié la régénération naturelle de Vouacapoua americana (wacapou), arbre de la forêt tropicale, sur le dispositif de la station scientifique des Nouragues, en Guyane française. En particulier, nous avons analysé l'effet de la densité en wacapous adultes sur les jeunes stades de la régénération situés sous la couronne et hors de la couronne des 33 arbres que nous avons étudiés. Globalement, nous avons observé une augmenta- tion du nombre de plants lorsque la densité en adulte augmente. Cela signifierait que la régénération du wacapou est possible même lorsque l'espèce est déjà très présente localement. Cependant nous discutons ce résultat en nous appuyant sur les connais- sances actuelles de la dynamique de l'espèce. En effet elle ne domine jamais le peuplement forestier. Un mécanisme doit donc s'opposer à ce que la densité en adultes puisse encore augmenter là où elle est déjà forte. Nos propres observations permettent également de tempérer le résultat obtenu puisque, dans plusieurs cas, il n'y a pas de régénération autour des arbres, en quelque situation de densité qu'ils se trouvent.
https://hal.archives-ouvertes.fr/hal-01189168

hal-01189168
https://hal.archives-ouvertes.fr/hal-01189168
PRODINRA : 11140

Éditeur(s) : HAL CCSD Elsevier
Résumé :  
absent
Ecology and management of a neotropical rainforest: lessons drawn from Paracou, a long-term experimental research site in French Guiana

ISBN : 2-84299-455-8
hal-01190909
https://hal.archives-ouvertes.fr/hal-01190909
PRODINRA : 73005

Éditeur(s) : HAL CCSD
Résumé :   Diplôme : DEA
il s'agit d'un type de produit dont les métadonnées ne correspondent pas aux métadonnées attendues dans les autres types de produit : DISSERTATION
absent
https://hal.archives-ouvertes.fr/hal-01189525

hal-01189525
https://hal.archives-ouvertes.fr/hal-01189525
PRODINRA : 45292

Éditeur(s) : HAL CCSD Oxford University Press (OUP): Policy B - Oxford Open Option B
Résumé : 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 massbased leaf N concentration and photosynthetic capacity were poor. Conversely, the species differed greatly in relativeNallocation to carboxylation and bioenergetics. Principal component analysis (PCA) revealed that, of the recorded traits, only the computed fraction of total leafNinvested in photosynthesis was tightly correlated to photosynthetic capacity.We also used PCAto 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 leafNconcentration, and that leaf traits related to photosynthetic capacity did not discriminate shade-tolerance ranking of these tropical tree species.
ISSN: 0829-318X

hal-01031522
https://hal.archives-ouvertes.fr/hal-01031522