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[797] Eperua falcata Aubl. Hist. Pl. Guiane 1: 369 [Jun.-Dec. 1775] (Aublet 1775). — Panzera falcata (Aubl.) Willd., Sp. Pl., ed. 4 2 (1): 540 [Mar. 1799] (Willdenow 1799). — Dimorpha falcata (Aubl.) Sm., Cycl. [Rees] 11: (Dimorpha no. 3) [3 Dec. 1808] (Smith 1808). NOTE. — Hyperdominant in Amazonia (ter Steege et al. 2020), although known only from the Guiana Shield. VERNACULAR NAMES. — Pa: wap, wap-duwõ • Ka: palɨwɨ, paliwu, tyoto amote, vouapa-tabaca (fide Aublet 1775), watapa • Te: tapaka’i • Wp: tapaka • Wn: wapa • Nt: bii udu, wapa • Cr: pwa-sab, wapa, wapa-gra • Fr: wapa • Br: apa, apazeiro, espadeira, muirapiranga. HERBARIUM DATA (FG). — 292 collections at CAY. Sel. exs.: J.B. Aublet s.n. (original material BM[BM000952284]). INVENTORY DATA (FG). — 3623 trees in 150 plots; Fmax = 14.7 %; dbhinv = 101 cm., Published as part of Molino, Jean-François, Sabatier, Daniel, Grenand, Pierre, Engel, Julien, Frame, Dawn, Delprete, Piero G., Fleury, Marie, Odonne, Guillaume, Davy, Damien, Lucas, Eve J. & Martin, Claire A., 2022, An annotated checklist of the tree species of French Guiana, including vernacular nomenclature, pp. 345-903 in Adansonia (3) (3) 44 (26) on page 514, DOI: 10.5252/adansonia2022v44a26, http://zenodo.org/record/7458777, {"references":["AUBLET J. - B. C. F. 1775. - Histoire des plantes de la Guyane francoise. Didot, Paris, 4 vol. https: // doi. org / 10.5962 / bhl. title. 674","WILLDENOW C. L. 1799. - Species plantarum, exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas, ed. 4. Vol. 2 (1). G. C. Nauk, Berlin, 823 p.","TER STEEGE H., PRADO P. I., LIMA R. A. F. DE, POS E., DE SOUZA COELHO L., DE ANDRADE LIMA FILHO D., SALOMAO R. P., AMARAL I. L., DE ALMEIDA MATOS F. D., CASTILHO C. V., PHILLIPS O. L., GUEVARA J. E., DE JESUS VEIGA CARIM M., CARDENAS LOPEZ D., MAGNUSSON W. E., WITTMANN F., MARTINS M. P., SABATIER D., IRUME M. V., DA SILVA GUI- MARAES J. R., MOLINO J. - F., BANKI O. S., PIEDADE M. T. F., PITMAN N. C. A., RAMOS J. F., MONTEAGUDO MENDOZA A., VENTICINQUE E. M., LUIZE B. G., NUNEZ VARGAS P., SILVA T. S. F., DE LEAO NOVO E. M. M., REIS N. F. C., TERBORGH J., MANZATTO A. G., CASULA K. R., HONORIO CORONADO E. N., MONTERO J. C., DUQUE A., COSTA F. R. C., CASTANO ARBOLEDA N., SCHONGART J., ZARTMAN C. E., KILLEEN T. J., MARIMON B. S., MARIMON- JUNIOR B. H., VASQUEZ R., MOSTACEDO B., DEMARCHI L. O., FELDPAUSCH T. R., ENGEL J., PETRONELLI P., BARALOTO C., ASSIS R. L., CASTELLANOS H., SIMON M. F., DE MEDEIROS M. B., QUARESMA A., LAUR- ANCE S. G. W., RINCON L. M., ANDRADE A., SOUSA T. R., CAMARGO J. L., SCHIETTI J., LAURANCE W. F., DE QUEIROZ H. L., NASCIMENTO H. E. M., LOPES M. A., DE SOUSA FARIAS E., MAGALHAES J. L. L., BRIENEN R., AYMARD C. G. A., RE- VILLA J. D. C., VIEIRA I. C. G., CINTRA B. B. L., STEVENSON P. R., FEITOSA Y. O., DUIVENVOORDEN J. F., MOGOLLON H. F., ARAUJO- MURAKAMI A., FERREIRA L. V., LOZADA J. R., COMISKEY J. A., DE TOLEDO J. J., DAMASCO G., DAVILA N., LOPES A., GARCIA- VILLACORTA R., DRAPER F., VICENTINI A., CORNEJO VALVERDE F., LLOYD J., GOMES V. H. F., NEILL D., ALONSO A., DALLMEIER F., DE SOUZA F. C., GRIBEL R., AR- ROYO L., CARVALHO F. A., DE AGUIAR D. P. P., DO AMARAL D. D., PANSONATO M. P., FEELEY K. J., BERENGUER E., FINE P. V. A., GUEDES M. C., BARLOW J., FERREIRA J., VILLA B., PENUELA MORA M. C., JIMENEZ E. M., LICONA J. C., CERON C., THOMAS R., MAAS P., SILVEIRA M., HENKEL T. W., STROPP J., PAREDES M. R., DEXTER K. G., DALY D., BAKER T. R., HUAMANTUPA- CHUQUIMACO I., MILLIKEN W., PENNINGTON T., TELLO J. S., PENA J. L. M., PERES C. A., KLITGAARD B., FUENTES A., SILMAN M. R., DI FIORE A., VON HILDEBRAND P., CHAVE J., VAN ANDEL T. R., HILARIO R. R., PHILLIPS J. F., RIVAS- TORRES G., NORONHA J. C., PRIETO A., GONZALES T., DE SA CARPANEDO R., GONZALES G. P. G., GOMEZ R. Z., DE JESUS RODRIGUES D., ZENT E. L., RUSCHEL A. R., VOS V. A., FONTY E., JUNQUEIRA A. B., DOZA H. P. D., HOFFMAN B., ZENT S., BARBOSA E. M., MALHI Y., DE MATOS BONATES L. C., DE ANDRADE MIRANDA I. P., SILVA N., BARBOSA F. R., VELA C. I. A., PINTO L. F. M., RUDAS A., ALBUQUERQUE B. W., UMANA M. N., CARRERO MARQUEZ Y. A., VAN DER HEI- JDEN G., YOUNG K. R., TIRADO M., CORREA D. F., SIERRA R., COSTA J. B. P., ROCHA M., VILANOVA TORRE E., WANG O., OLIVEIRA A. A., KALAMANDEEN M., VRIESENDORP C., RAMIREZ- ANGULO H., HOLMGREN M., NASCIMENTO M. T., GALBRAITH D., FLORES B. M., SCUDELLER V. V., CANO A., AHUITE REATEGUI M. A., MESONES I., BAIDER C., MENDOZA C., ZAGT R., URREGO GIRALDO L. E., FERREIRA C., VILLARROEL D., LINARES- PALOMINO R., FARFAN- RIOS W., FARFAN- RIOS W., CASAS L. F., CARDENAS S., BALSLEV H., TORRES- LEZAMA A., ALEXIADES M. N., GARCIA- CABRERA K., VALENZUELA GAMARRA L., VALDERRAMA SANDOVAL E. H., RAMIREZ AREVALO F., HER- NANDEZ L., SAMPAIO A. F., PANSINI S., PALACIOS CUENCA W., DE OLIVEIRA E. A., PAULETTO D., LEVESLEY A., MELGACO K. & PICKAVANCE G. 2020. - Biased-corrected richness estimates for the Amazonian tree flora. Scientific Reports 10 (1): 10130. https: // doi. org / 10.1038 / s 41598 - 020 - 66686 - 3"]}

Eperua falcata Aublet (1775: 369) Lectotype (designated by Cowan 1975): — FRENCH GUIANA. Cayenne, s.d. [July 1762 – July 1764], J.B.C.F. Aublet s.n. (BMinflorescence [000952284] image!). ≡ Dimorpha falcata (Aubl.) Forsyth (1794: 391) nom. illeg. superfl. ≡ Panzera falcata (Aubl.) Willdenow (1799: 540), nom. illeg. superfl. ≡ Dimorpha falcata (Aubl.) Smith in Rees (1808: 656), nom. illeg. superfl. In his work, Histoire des plantes de la Guiane Françoise, Aublet described 576 genera and 1241 plant species (Leandri 1968) based on his collections, including E. falcata. We checked all herbaria cited in the taxonomic literature (Stafleu & Cowan 1976) where it is possible to find Aublet’s collections, but we found only one specimen of E. falcata in BM. There is another sterile collection in P, J.B.C.F. Aublet 8288, originally identified as E. falcata, but characteristics of the leaflets indicate that the specimen is probably E. rubiginosa. Although there is only one specimen, Cowan (1975) needed to designate a lectotype to E. falcata restricted to the inflorescence on the BM sheet, as the vegetative part represents other Eperua species, probably E. rubiginosa. Cowan (1975) cited “ Cayenne 1775 ” as the location and date of the type collection, and the note “ Cayenne Mr. Fusée Aublet 1773 ” is handwritten on the sheet. However, none of these years corresponds to the actual collection date, since Aublet collected the sample in French Guiana between July 1762 and July 1764, leaving the country in July 1764 (Aublet 1775, Froidevaux 1897). Besides the absence of vegetative parts in the sheet, Aublet (1775) presents a poorly detailed description and a plate. Nevertheless, Aublet’s description and plate clearly refer to E. falcata. Among the diagnostic characteristics of E. falcata are falcate leaflets and pendent lateral racemes. These characteristics differentiate it from E. rubiginosa, which has straight leaflets and erect lateral racemes. In addition, E. falcata is clearly distinct from related species with falcate leaflets and pendent inflorescences such as E. leucantha and E. venosa. Aublet’s plate presents a 3-jugate leaf differing from E. venosa that always has 2-jugate leaves. E. falcata ’s plate and type sheet show long lateral racemes with many brownish buds, contrasting with the noticeable shorter lateral racemes with fewer and larger gray buds of E. leucantha., Published as part of Fortes, Elenice A. & Mansano, Vidal F., 2022, Untangling nomenclatural issues of some Amazonian trees of Eperua Aubl. (Leguminosae, Detarioideae, Detariae), pp. 189-198 in Phytotaxa 542 (2) on page 192, DOI: 10.11646/phytotaxa.542.2.6, http://zenodo.org/record/6417751, {"references":["Aublet, J. B. C. F. (1775) Histoire des plantes de la Guiane Francoise. Tome I and Tome II. Pierre Francoies Didot jeune, Paris, 976 pp.","Cowan, R. S. (1975) Monograph of the genus Eperua (Leguminosae: Caesalpinioideae). Smithsonian Contributions to Botany 28: 1 - 45. https: // doi. org / 10.5479 / si. 0081024 X. 28","Forsyth, Jr., W. (1794) A Botanical nomenclator containing a systematical arrangement of the classes, orders, genera, and species of plants as described in the new edition of Linnaesus's Systema naturae, by Dr. Gmelin. Printed for T. Cadell, and P. Elmsly, in the Strand, and G. Nicol, Pall-Mall, London, p. 391. https: // doi. org / 10.5962 / bhl. title. 127458","Willdenow, C. L. (1799) Species plantarum, ed. 4, 2 (1). G. C. Nauk, Berolini, 823 pp.","Rees, A. (1808) The cyclopaedia; or, Universal dictionary of arts, sciences, and literature. Vol. 11. Longman, Hurst, Rees, Orme & Brown, Paternoser-Row, London, 768 pp.","Leandri, J. (1968) Un pharmacien provencal decouvre une partie de la flore du Nouveau Monde: J. B. C. Fusee Aublet et l' \" Histoire des plantes de la Guyane francaise \". Adansonia 8 (2): 137 - 146.","Stafleu, F. A. & Cowan, R. S. (1976) Taxonomic literature: a selective guide to botanical publications and collections with dates, commentaries and types. Volume I: A-G. Regnum Vegetabile 137. Bohn, Scheltema & Holkema, Utrecht, 1136 pp. Available from: https: // www. biodiversitylibrary. org / item / 103414 page / 11 / mode / 1 up (accessed 6 November 2011.","Froidevaux, H. (1897) Etude sur les recherches scientifiques de Fusee Aublet a la Guyane francaise 1762 - 1764. Kessinger Publishing, United States, 52 pp."]}

Plant populations are able to undergo very localized adaptive processes, that allow continuous populations to adapt to divergent habitats in spite of recurrent gene flow. Here, we carried out a genome scan for selection through whole-genome sequencing of pools of populations, sampled according to a nested sampling design, to evaluate microgeographic adaptation in the hyperdominant Amazonian tree Eperua falcata Aubl. (Fabaceae). A high-coverage genomic resource of ~250 Mb was assembled de novo and annotated, leading to 32 789 predicted genes. 97 062 bi-allelic SNPs were detected in 25 803 contigs were detected, and a custom Bayesian model we implemented to uncover candidate genomic targets of divergent selection. A set of 290 'divergence' outlier SNPs was detected at the regional scale (between study sites), while 185 SNPs located in the vicinity of 106 protein-coding genes were detected as replicated outliers between microhabitats within regions. These genes possibly underlie ecologically important phenotypes and tend to indicate that adaptation to microgeographic habitat patchiness would affect genomic regions involved in a variety of physiological processes, among which plant response to stress (for e.g., oxidative stress, hypoxia and metal toxicity) and biotic interactions. Identification of genomic targets of microgeographic adaptation in the Neotropics supports the hypothesis - frequently raised at the community level - that local adaptation would be a key driver of ecological diversification, probably operating across multiple spatial scales, from large- (i.e. regional) to microgeographic- (i.e. landscape) scales.

Local adaptation to microgeographic habitat patchiness in Amazonian trees: example of the hyperdominant [i]Eperua falcata[/i] (Aubl.). ATBC 2016

Modelling the local density of tropical saplings can provide insights into the ecological processes that drive species regeneration and thereby help predict population recovery after disturbance. Yet, few studies have addressed the challenging issues in autocorrelation and zero-inflation of local density. This paper presents Hierarchical Bayesian Modelling (HBM) of sapling density that includes these two features. Special attention is devoted to variable selection, model estimation and comparison. We developed a Zero-Inflated Poisson (ZIP) model with a latent correlated spatial structure and compared it with non-spatial ZIP and Poisson models that were either autocorrelated (Spatial Generalized Linear Mixed, SGLM) or not (generalized linear models, GLM). In our spatial models, local density autocorrelation was modeled by a Conditional Auto-Regressive (CAR) process. 13 explicative variables described ecological conditions with respect to topography, disturbance, stand structure and intraspecific processes. Models were applied to six tropical tree species with differing biological attributes: Oxandra asbeckii , Eperua falcata , Eperua grandiflora , Dicorynia guianensis , Qualea rosea , and Tachigali melinonii . We built species-specific models using a simple method of variable selection based on a latent binary indicator. Our spatial models showed a close correlation between observed and estimated densities with site spatial structure being correctly reproduced. By contrast, the non-spatial models showed poor fits. Variable selection highlighted species-specific requirements and susceptibility to local conditions. Model comparison overall showed that the SGLM was the most accurate explanatory and predictive model. Surprisingly, zero-inflated models performed less well. Although the SZIP model was relevant with respect to data distribution, and more flexible with respect to response curves, its model complexity caused marked variability in parameter estimates. In the SGLM, the spatial process alone accounted for zero-inflation in the data. A refinement of the hypotheses employed at the process level could compensate for distribution flaws at the data level. This study emphasized the importance of the HBM framework in improving the modelling of density–environment relationships.

Background. In wild plant populations, genetic divergence within continuous stands is common, sometimes at very short geographical scales. While restrictions to gene flow combined with local inbreeding and genetic drift may cause neutral differentiation among subpopulations, microgeographical variations in environmental conditions can drive adaptive divergence through natural selection at some targeted loci. Such phenomena have recurrently been observed in plant populations occurring across sharp environmental boundaries, but the interplay between selective processes and neutral genetic divergence has seldom been studied.[br/]Methods. We assessed the extent of within-stand neutral and environmentally-driven divergence in the Neotropical tree [i]Eperua falcate Aubl[/i]. (Fabaceae) through a genome-scan approach. Populations of this species grow in dense stands that cross the boundaries between starkly contrasting habitats. Within-stand phenotypic and candidate-gene divergence have already been proven, making this species a suitable model for the study of genome-wide microgeographic divergence. Thirty trees from each of two habitats (seasonally flooded swamps and well-drained plateaus) in two separate populations were genotyped using thousands of AFLPs markers. To avoid genotyping errors and increase marker reliability, each sample was genotyped twice and submitted to a rigorous procedure for data cleaning, which resulted in 1196 reliable and reproducible markers.[br/]Results. Despite the short spatial distances, we detected within-populations genetic divergence, probably caused by neutral processes, such as restrictions in gene flow. Moreover, habitat-structured subpopulations belonging to otherwise continuous stands also diverge in relation to environmental variability and habitat patchiness: we detected convincing evidence of divergent selection at the genome-wide level and for a fraction of the analyzed loci (comprised between 0.25% and 1.6%). Simulations showed that the levels of differentiation for these outliers are compatible with scenarios of strong divergent selection

Within tree communities, the differential use of soil N mineral resources, a key factor in ecosystem functioning, may reflect functional complementarity, a major mechanism that could explain species coexistence in tropical rainforests. Eperua falcata and Dicorynia guianensis, two abundant species cooccurring in rainforests of French Guiana, were chosen as representative of two functional groups with complementary N uptake strategies (contrasting leaf δ15N signatures related to the δ15N of their soil N source, NO3- or NH4+). The objectives were to investigate if these strategies occurred under contrasted soil N resources in sites with distinct geological substrates representative of the coastal rainforests. Results showed that species displayed contrasting leaf δ15N signatures on both substrates, confirming their complementary N uptake strategy. Consequently, their leaf 15N can be used to trace the presence of inorganic N-forms in soils (NH4+ and NO3-) and thus to indicate the capacity of soils to provide each of these two N sources to the plant community.

Background The Amazonian rainforest is predicted to suffer from ongoing environmental changes. Despite the need to evaluate the impact of such changes on tree genetic diversity, we almost entirely lack genomic resources. Results In this study, we analysed the transcriptome of four tropical tree species (Carapa guianensis, Eperua falcata, Symphonia globulifera and Virola michelii) with contrasting ecological features, belonging to four widespread botanical families (respectively Meliaceae, Fabaceae, Clusiaceae and Myristicaceae). We sequenced cDNA libraries from three organs (leaves, stems, and roots) using 454 pyrosequencing. We have developed an R and bioperl-based bioinformatic procedure for de novo assembly, gene functional annotation and marker discovery. Mismatch identification takes into account single-base quality values as well as the likelihood of false variants as a function of contig depth and number of sequenced chromosomes. Between 17103 (for Symphonia globulifera) and 23390 (for Eperua falcata) contigs were assembled. Organs varied in the numbers of unigenes they apparently express, with higher number in roots. Patterns of gene expression were similar across species, with metabolism of aromatic compounds standing out as an overrepresented gene function. Transcripts corresponding to several gene functions were found to be over- or underrepresented in each organ. We identified between 4434 (for Symphonia globulifera) and 9076 (for Virola surinamensis) well-supported mismatches. The resulting overall mismatch density was comprised between 0.89 (S. globulifera) and 1.05 (V. surinamensis) mismatches/100 bp in variation-containing contigs. Conclusion The relative representation of gene functions in the four transcriptomes suggests that secondary metabolism may be particularly important in tropical trees. The differential representation of transcripts among tissues suggests differential gene expression, which opens the way to functional studies in these non-model, ecologically important species. We found substantial amounts of mismatches in the four species. These newly identified putative variants are a first step towards acquiring much needed genomic resources for tropical tree species. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-238) contains supplementary material, which is available to authorized users.

In the tropical rainforest of Amazonia, the factors driving the evolution of tree species remain poorly understood, and the relative influence of neutral and adaptive processes is continuously debated. In particular, local habitat patchiness draws much attention, as profound changes in the structure and composition of forest communities occur among micro-habitats. Thus, micro-environmental variations related to topography have frequently been invoked as drivers of adaptive radiation leading to sympatric speciation in Neotropical trees. On one hand, the hypothesis of local adaptation has never been investigated at the intra-specific level, i.e. within species currently undergoing population differentiation; on the other hand, many tree species are genetically structured over local scales due to neutral processes, mainly limited gene flow (caused by restricted pollen and seed dispersal). In this study, I used populations of a common tree species of the Guiana Shield - Eperua falcata (Fabaceae) - to study how neutral and adaptive processes shape the distribution of genetic diversity across forest landscapes characterized by local micro-habitat patchiness. I asked three main questions by combining both phenotypic (quantitative genetics) and molecular (population genetics) approaches: 1) How is the genetic diversity structured in forest landscapes of French Guiana? 2) Which evolutionary drivers are relevant to explain the structure of genetic diversity at local scale? 3) Does local adaptation contribute to structure genetic diversity within continuous populations?, En forêt tropicale humide Amazonienne, les facteurs gouvernant l'évolution des espèces d'arbres restent peu connus et continuellement débattus. En particulier, les micro-variations environnementales attirent beaucoup d'attention car elles induisent de profondes modifications de structure et composition des communautés. Les variations micro-environnementales associées à la topographie ont couramment été évoquées comme facteur de radiations adaptatives chez les espèces d'arbres. Cependant, l'hypothèse de l'adaptation locale n'a jamais été testée au niveau intra-spécifique chez les arbres de forêt amazonienne alors que l'on sait que la diversité génétique des arbres tropicaux est couramment structurée à faibles échelles spatiales par des processus neutres (en particulier du fait de restrictions de flux de gènes). Dans cette étude, j'ai étudié le processus de différentiation génétique d'une espèce d'arbre (Eperua falcata, Fabaceae) dans les paysages forestiers de Guyane française grâce à la combinaison d'une approche phénotypique (génétique quantitative) et d'une approche moléculaire (génétique des populations). Je me suis attachée à répondre à trois questions principales : 1) Comment se distribue la diversité génétique dans les paysages forestiers de Guyane française ? 2) Quelles forces évolutives sont impliquées dans le processus de différentiation génétique à faible échelle spatiale ? 3) Est-ce que le processus d'adaptation locale contribue à structurer la diversité génétique à faible échelle spatiale ?

† Background and Aims In habitat mosaics, plant populations face environmental heterogeneity over short geographical distances. Such steep environmental gradients can induce ecological divergence. Lowland rainforests of the Guiana Shield are characterized by sharp, short-distance environmental variations related to topography and soil characteristics (from waterlogged bottomlands on hydromorphic soils to well-drained terra firme on ferralitic soils). Continuous plant populations distributed along such gradients are an interesting system to study intrapopulation divergence at highly local scales. This study tested (1) whether conspecific populations growing in different habitats diverge at functional traits, and (2) whether they diverge in the same way as congeneric species having different habitat preferences. † Methods Phenotypic differentiation was studied within continuous populations occupying different habitats for two congeneric, sympatric, and ecologically divergent tree species (Eperua falcata and E. grandiflora, Fabaceae). Over 3000 seeds collected from three habitats were germinated and grown in a common garden experiment, and 23 morphological, biomass, resource allocation and physiological traits were measured. † Key Results In both species, seedling populations native of different habitats displayed phenotypic divergence for several traits (including seedling growth, biomass allocation, leaf chemistry, photosynthesis and carbon isotope composition). This may occur through heritable genetic variation or other maternally inherited effects. For a sub-set of traits, the intraspecific divergence associated with environmental variation coincided with interspecific divergence. † Conclusions The results indicate that mother trees from different habitats transmit divergent trait values to their progeny, and suggest that local environmental variation selects for different trait optima even at a very local spatial scale. Traits for which differentiation within species follows the same pattern as differentiation between species indicate that the same ecological processes underlie intra- and interspecific variation.

Unveiling the genetic basis of local adaptation to environmental variation is a major goal in molecular ecology. In rugged landscapes characterized by environmental mosaics, living populations and communities can experience steep ecological gradients over very short geographical distances. In lowland tropical forests, interspecific divergence in edaphic specialization (for seasonally flooded bottomlands and seasonally dry terra firme soils) has been proven by ecological studies on adaptive traits. Some species are nevertheless capable of covering the entire span of the gradient; intraspecific variation for adaptation to contrasting conditions may explain the distribution of such ecological generalists. We investigated whether local divergence happens at small spatial scales in two stands of Eperua falcata (Fabaceae), a widespread tree species of the Guiana Shield. We investigated Single Nucleotide Polymorphisms (SNP) and sequence divergence as well as spatial genetic structure (SGS) at four genes putatively involved in stress response and three genes with unknown function. Significant genetic differentiation was observed among sub-populations within stands, and eight SNP loci showed patterns compatible with disruptive selection. SGS analysis showed genetic turnover along the gradients at three loci, and at least one haplotype was found to be in repulsion with one habitat. Taken together, these results suggest genetic differentiation at small spatial scale in spite of gene flow. We hypothesize that heterogeneous environments may cause molecular divergence, possibly associated to local adaptation in E. falcata.

International audience; Wallaba (Eperua falcata) is a tropical wood which is known to have naturally low swelling characteristics. Samples of wallaba heartwood were subjected to differential solvent extraction. Wood pieces that were extracted with methanol experienced significantly higher swelling after rehydration from oven dry to 96% relative humidity in comparison to non-extracted samples and samples extracted with other solvents. Methanol soluble wallaba heartwood extract was purified by high pressure liquid chromatography and the compounds present were characterised by nuclear magnetic resonance spectroscopy. Methanol extract was found to contain a very high relative proportion of polar compounds which are proposed to bind to the polymeric cell wall by multiple hydrogen bonds restricting the association of water and therefore acting as natural anti-swelling agents.

International audience; A comparative study of 9H-pyrido[3,4-b]indole (norharmane) and 1-methyl-9H-pyrido[3,4-b]indole (harmane) as inhibitors for C38 steel corrosion in 1 M HCl solution at 25 °C was carried out. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were applied to study the metal corrosion behavior in the absence and presence of different concentrations of these inhibitors. The OCP as a function of time were also established. Cathodic and anodic polarization curves show that norharmane and harmane are a mixed-type inhibitors. Adsorption of indole derivatives on the C38 steel surface, in 1 M HCl solution, follows the Langmuir adsorption isotherm model. The ΔGads values were calculated and discussed. The potential of zero charge (PZC) of the C38 steel in inhibited solution was studied by the EIS method, and a mechanism for the adsorption process was proposed. Raman spectroscopy confirmed that indole molecules strongly adsorbed onto the steel surface. The electronic properties of indole derivates, obtained using the AM1 semi-empirical quantum chemical approach, were correlated with their experimental efficiencies using the linear resistance model (LR).

International audience; Gravitropism is necessary for plants to control the orientation of their axes while they grow in height. In woody plants, stem re-orientations are costly because they are achieved through diameter growth. The functional diversity of gravitropism was studied to check if the mechanisms involved and their efficiency may contribute to the differentiation of height growth strategies between forest tree species at the seedling stage. Seedlings of eight tropical species were grown tilted in a greenhouse, and their up-righting movement and diameter growth were measured during three months. Morphological, anatomical and biomechanical traits were measured at the end of the survey. Curvature analysis was used to analyse the up-righting response along the stems. Variations in stem curvature depend on diameter growth, size effects, the increase in self-weight, and the efficiency of the gravitropic reaction. A biomechanical model was used to separate these contributions. Results showed that (1) gravitropic movements were based on a common mechanism associated to similar dynamic patterns, (2) clear differences in efficiency (defined as the change in curvature achieved during an elementary diameter increment for a given stem diameter) existed between species, (3) the equilibrium angle of the stem and the anatomical characters associated to the efficiency of the reaction also differed between species, (4) the differences in gravitropic reaction were related to the light requirements: heliophilic species, compared to more shade-tolerant species, had a larger efficiency and an equilibrium angle closer to vertical. This suggests that traits determining the gravitropic reaction are related to the strategy of light interception and may contribute to the differentiation of ecological strategies promoting the maintenance of biodiversity in tropical rain forests.

Summary Designing permanent sample plots is a key issue in forestry where long-term data are required to assess the sustainability of forest logging. The data that are collected in permanent sample plots are used to set parameters in a population dynamics matrix model which in turn is used to predict stock recovery rates for each species. The sampling plan for permanent plots can be designed to estimate stock recovery rates with a required accuracy at a given confidence level, while minimizing installation costs. This can be formulated as a constrained optimization problem (one constraint for each species). The question then is to quantify sampling variability, i.e. the variability of model predictions that are generated by the distribution of parameter estimators. In this study, we address the question of sampling variability for a size-classified population matrix model in a hierarchical context where sample size is itself random and driven by a multivariate spatial point process. An approximate expression is given for the accuracy of the stock recovery rate estimator. This expression is the limit of the accuracy as the expectation of sample size tends to ∞. We extend this expression to the multispecies case. To a first approximation, interactions between species do not affect the accuracy of the stock recovery rate for each species. A sampling plan is designed using the data for three species in a tropical rainforest in French Guiana. The optimal sampling plan appears to be determined by the most constrained species.

The chemical analysis of the compounds present in dichloromethane and ethanolic fractions as well as bioassays enable to understand the differences in the durability of Eperua falcata and Eperua grandiflora. The main distinction between these two species is the acidic subfraction of diterpenoid extract, which is antifungal in Eperua falcata when tested under in-vitro conditions. This study also shows that ethanolic fraction plays an important role in the mechanism of natural durability. Furthermore, it reports the first isolation of cativic acid in Eperua falcata wood.

Previous studies in lowland tropical rainforests of French Guiana showed that, among non-N 2 -fixing trees, two groups of late successional species contrasting in their leaf 15 N natural abundance coexist, suggesting two different main ways of nitrogen acquisition. Two abundant late-successional species typically co-occurring in rainforests in French Guiana, namely Eperua falcata and Dicorynia guianensis, were chosen as representative of each group. Stable isotope techniques and measurements of potentials of microbial N transformation were performed to assess to what extent leaf 15 N natural abundance of these species could be related to (i) δ 15 N signatures of soil mineral N sources and (ii) the capacity of soil to express nitrification and denitrification (both processes being directly involved in the balance between NH 4 + and NO 3 – ). Soil δ 15 N-NH 4 + was roughly similar to leaf δ 15 N of D. guianensis (around 3.5‰), suggesting a preferential use of NH 4 + , whereas in E. falcata, leaf δ 15 N values were closer to root δ 15 N-NO 3 − values (0.2 and −2.0‰, respectively), suggesting a preferential use of NO 3 − . These differences in N source utilization were not accompanied by differences in availability in soil NO 3 − or in intensity of microbial functions responsible for soil N mineral evolution. However, (i) under both tree species, these functions showed clear spatial partitioning, with denitrification occurring potentially in soil and nitrification in the litter layer, and (ii) E. falcata fine roots colonized the litter layer much more strongly than D. guianensis fine roots. This strongly suggests that (i) the contrasted leaf δ 15 N values found in the two late-successional species reveal distinct N acquisition strategies and (ii) the ability of roots to predominantly exploit the litter layer ( E. falcata ) or the soil ( D. guianensis ) may constitute an important explanation of the observed differences. A complementarity between tree species, based on mineral N resource partitioning (itself resulting from a spatially structured location of the microbial functions responsible for the balance between NH 4 + and NO 3 – ), can thus be supposed.

On 10 trees from 10 species of French Guyana tropical rainforest in a clear active process of restoring verticality growth strains were measured in situ in order to determine the occurrence of tension wood within samples. Wood specimens were cut in the vicinity of the growth strains measurements in order to measure some mechanical and physical properties. As suspected, tensile growth strains was very much higher in tension wood zone, because longitudinal modulus of elasticity was slightly higher. Longitudinal shrinkage was also much higher in tension wood than in opposite wood., Des mesures de contraintes de croissance ont été réalisées sur 10 arbres en cours de redressement actif appartenant à 10 espèces de la forêt tropicale humide de Guyane Française afin de s'assurer de la présence de bois de tension. Des échantillons de bois, prélevés au voisinage des mesures de contraintes de croissance, ont permis de mesurer un certains nombres de propriétés physiques et mécaniques. Comme présumé les contraintes de croissance sont beaucoup plus élevées au niveau du secteur de bois de tension, car le module d'élasticité est légèrement plus élevé. Le retrait longitudinal est aussi plus élevé dans le bois de tension que dans le bois opposé.

L'objectif de ce travail était d'étudier la plasticité des traits fonctionnels relatifs à la photosynthèse en fonction du type de sol chez Eperua falcata, une espèce forestière de Guyane française. Les individus ont été échantillonnés sur deux sols contrastés : sol de bas-fond (Gleysol) à fort hydromorphisme, et sol de crête (Ferralsol) à drainage vertical libre. Le micro climat lumineux a été quantifié au-dessus de chaque individu. Les capacités photosynthétiques (vitesse maximale de carboxylation du RuBP, Vcmax, et flux maximal d'électrons photosynthétiques, Jmax) ont été estimées en ajustant un modèle biochimique de photosynthèse foliaire (Farquhar et al. 1980), sur des courbes de réponse de l'assimilation nette du C02 en fonction de la concentration interne en CO2, sous fort éclairement (courbe A-Ci). Les résultats obtenus ont montré un effet du type de sol sur les capacités photosynthétiques foliaires et que celles-ci étaient plutôt liées à des modifications des allocations d'azote aux processus de carboxylation Pc et à la bioénergétique Pb plutôt qu'à des changements structuraux foliaires. Les résultats ont également mis en évidence des différentiels dans les seuils de sensibilité à la lumière selon le type de trait foliaire avec, grande sensibilité à de faibles variations du micro climat lumineux pour les capacités de photosynthèse et une absence de sensibilité à ces mêmes variations pour les traits structuraux.

This work aimed at understanding the role of mycorrhizal status in phosphorus efficiency of tree seedlings in the tropical rainforest of French Guyana. * Mycorrhizal colonization, growth, phosphorus content, net photosynthesis and root respiration were determined on three occasions during a 9-month growth period for seedlings of two co-occurring species (Dicorynia guianensis and Eperua falcata) grown at three soil phosphorus concentrations, with or without inoculation with arbuscular mycorrhizas. * Seedlings of both species were unable to absorb phosphorus in the absence of mycorrhizal association. Mycorrhizal seedlings exhibited coils that are specific of Paris-type mycorrhizae. Both species benefited from the mycorrhizal symbiosis in terms of phosphorus acquisition but the growth of E. falcata seedlings was unresponsive to this mycorrhizal improvement of phosphorus status, probably because of the combination of high seed mass and P reserves, with low growth rate. * The two species belong to two different functional groups regarding phosphorus acquisition, D. guianensis being an obligate mycotrophic species.

Il existe une grande variabilité de la résistance des bois aux agents de dégradation chez les espèces tropicales, qu'il faut maîtriser pour augmenter leur potentiel d'utilisation, notamment en Guyane. La thèse aborde deux problématiques : comment caractériser les structures de la variabilité intra-spécifique (inter et intra-arbre) de la résistance aux champignons basidiomycètes chez des espèces durables et surtout très variables ? Quel est le rôle des différentes familles chimiques d'extraits dans la durabilité naturelle en comparant des espèces botaniquement proches (Eperua falcata et Eperua grandiflora) très durable d'une part, durable et variable d'autre part. La dUrabilité naturelle a été étudiée au travers de différents types d'essais. Elle est peu influencée par la hauteur de prélèvement, mais elle diminue du duramen externe vers le duramen interne. Il existe une corrélation significative mais peu étroite entre la couleur du bois et sa durabilité naturelle. La résistance de l'Angélique est liée au paramètre "a*" (axe rouge-vert du système CIELAB). De même pour le Wapa courbaril, les arbres présentant les valeurs de "a*" les plus élevées sont les plus résistants. Enfin, pour ce qui concerne déterminisme chimique de la durabilité naturelle, les essais réalisés en conditions in-vivo ont montré que seuls les composés diterpénoïques, participent activement au mécanisme de la durabilité naturelle pour les deux espèces de Wapa. Les résultats des analyses chimiques expliquent en partie les structures de variabilité observées pour la durabilité et la couleur d'Eperua grandilora.

En Guyane française où les sols sont généralement acides et pauvres en éléments minéraux, la forêt est caractérisée par sa plurispécificité. Une approche de type écologique a montré, dans les racines des principales espèces forestières, la dominance d'endomycorhizes à structure intracellulaire particulière : des hyphes de type Paris, spiralé. Leur rôle dans l'acquisition du phosphore a été étudié expérimentalement chez deux Césalpiniacées. Les semis d'Angélique, Dicorynia guianensis Amshoff, sont très dépendants, pour leur croissance et leur teneur en phosphore, des mycorhizes à mycélium spiralé ; ce type de mycélium représente plus de 90 % de la colonisation fongique. Par contre, les semis de Wapa (Eperua falcata Aublet) forment également des mycorhizes mais ces dernières améliorent le statut phosphaté et sont sans effet sur la croissance de cette espèce. Ces résultats contribuent à la compréhension du rôle des symbioses endomycorhiziennes dans le processus de régénération naturelle et ouvrent des perspectives de recherche quant à leur intervention éventuelle dans le maintien de la diversité forestière.

International audience; En Guyane française où les sols sont généralement acides et pauvres en éléments minéraux, la forêt est caractérisée par sa plurispécificité. Une approche de type écologique a montré, dans les racines des principales espèces forestières, la dominance d'endomycorhizes à structure intracellulaire particulière : des hyphes de type Paris, spiralé. Leur rôle dans l'acquisition du phosphore a été étudié expérimentalement chez deux Césalpiniacées. Les semis d'Angélique, Dicorynia guianensis Amshoff, sont très dépendants, pour leur croissance et leur teneur en phosphore, des mycorhizes à mycélium spiralé ; ce type de mycélium représente plus de 90 % de la colonisation fongique. Par contre, les semis de Wapa (Eperua falcata Aublet) forment également des mycorhizes mais ces dernières améliorent le statut phosphaté et sont sans effet sur la croissance de cette espèce. Ces résultats contribuent à la compréhension du rôle des symbioses endomycorhiziennes dans le processus de régénération naturelle et ouvrent des perspectives de recherche quant à leur intervention éventuelle dans le maintien de la diversité forestière.

1. Objectifs: Cette mission avait trois objectifs principaux: - rencontrer, à l'occasion de l'installation de Lilian Blanc en Guyane, les principaux partenaires de notre équipe, afin de leur présenter les axes de recherche sur lesquels nous nous investissons et que nous allons développer dans les années à venir; - faire le point de l'état d'avancement et des difficultés rencontrées sur différentes opérations en cours (Placettes permanentes, Angélique, inventaire Paracou et ARBOCEL); - mettre en route le travail de 6 mois de Fabien Bouchet-Lannat, stagiaire INA-PG intervenant dans le projet "Placettes permanentes", ainsi que le travail de Jean-Gaël Jourget, nouveau VCAT de l'équipe.

The objective of this study was to examine the water relations and hydraulic architecture and vulnerability to cavitation in Virola surinamensis and V. michelii and to compare to similar measurements in Eperua falcata. In several previous reports Virola was seen to have a rather narrow range of xylem pressure potentials (Ψx) near zero in the course of a wet-season day while having water fluxes quite close to Eperua. We tested the hypothesis that the narrow range of Ψx might be consistent with very high hydraulic conductivities of stems, roots and shoots and high vulnerability to cavitation in Virola compared to Eperua. When this hypothesis proved false we concluded that the previous determinations of Ψx might be wrong in Virola due to latex. We re-examined the determination of Ψx in Virola by the pressure chamber technique and compared results to determination of Ψleaf by the thermocouple psychrometer technique and found that the likely range of Ψx are more negative than previously reported. Problems concerning the determination of Ψx in species with latex are discussed.

We inferred water acquisition patterns of two major tropical rainforest canopy tree species, during wet and dry seasons in different soil drainage conditions, based on the natural abundance of O-18 in soil and xylem water and on descriptions of the vertical extension of root systems. Vertical O-18 patterns in the soil were not monotonic and spatially distinct soil layers displayed similar O-18 values. Therefore, vertical patterns of water extraction could only be interpreted by combining the isotopic data with observed root and soil moisture vertical distributions. On sites with deep vertical drainage (DVD), Eperua falcata was able to absorb water down to at least -3.0 m depth, whereas Dicorynia guianensis depended solely on superficial layers. On sites with superficial lateral drainage (SLD), the rooting system of both species was less deep, but Eperua falcata was still able to extract water around -2.0 m depth. Despite these distinct patterns, there was no effect of seasonal soil drought on leaf water status. In terms of adaptation to seasonal soil drought, the strategy of Eperua falcata might be advantageous under occasional severe soil moisture stress, Nous avons estimé la distribution verticale de l'acquisition de l'eau chez deux espèces abondantes de la strate arborée supérieure en forêt tropicale humide, en saison sèche et en saison des pluies, pour des sols qui diffèrent par le type de drainage. Nous avons combiné une approche basée sur les mesures d'abondance naturelle en 18O de l'eau dans le sol et dans l'aubier, et une approche basée sur la description de l'extension verticale du système racinaire des arbres. Les variations de d18O en fonction de la profondeur ne sont pas monotones, des valeurs similaires de d18O sont observées pour plusieurs horizons de profondeurs distinctes. L'interprétation des profils verticaux d'extraction d'eau n'est possible qu'en combinant les données isotopiques et les données relatives aux profils de prospection racinaire et de variations saisonnières d'humidité du sol. Sur le site à drainage vertical libre (DVD), Eperua falcata est capable d'absorber de l'eau jusqu'à 3.0 m de profondeur au moins, alors que l'alimentation en eau de Dicorynia guianensis repose essentiellement sur les horizons supérieurs. Sur le site à drainage superficiel et latéral (SLD), le système racinaire des deux espèces est moins profond, mais Eperua falcata puise tout de même de l'eau jusqu'à –2.0 m de profondeur. Malgré ces différences de profondeur d'extraction de l'eau, l'état hydrique des arbres est maintenu constant en saison sèche et en saison des pluies. En termes d'adaptation à la sécheresse du sol, la stratégie d'Eperua falcata pourrait présenter des avantages lors de sécheresses exceptionnelles

Pour comprendre le comportement macroscopique du bois, il est interessant de connaitre ses proprietes a l'echelle microscopique. Pour cela, diverses techniques d'imagerie nous donnent des informations sur la structure geometrique en deux ou trois dimensions, la composition chimique, la densite ainsi que la presence de reseaux cristallins et leurs orientations. Les proprietes mecaniques sont souvent estimees, soit par des essais sur fibre isolee, soit par modelisation a partir des donnees de rigidite des differents constituants pris hors contexte cellulaire. Aujourd'hui, seules les techniques de nano-indentation permettent une estimation des proprietes mecaniques locales in situ, en un nombre limite de point de mesure. La microscopie acoustique permet la caracterisation des rigidites au niveau local pour des materiaux a forte rigidite (metaux, verres, ceramiques...). L'utilisation de cet outil pour des materiaux beaucoup moins rigides comme le bois, necessite la mise au point d'une procedure experimentale specifique. Les essais realises sur un microscope acoustique en reflexion ont montre que pour des images a fort grossissement, l'utilisation de coupes minces (~ 5 µm) apres inclusion dans la resine avec respectivement l'eau ou une solution d'iodure de potassium comme liquide de couplage a 600 MHz ou a 1 GHz donnait des resultats permettant d'envisager une analyse des rigidites locales a partir des niveaux de gris de l'image acoustique. ––––– To understand wood macroscopic behaviour, it is useful to know its properties at the microscopic level. For this, several imaging techniques can provide information about the geometrical structure in 2 or 3 dimensions, chemical composition, density, crystal lattice and crystal orientation. Wood mechanical properties are determined either by testing isolated fibre, or trough modelling based on stiffness data of the various cell wall components obtained outside the cellular context. Only nanoindentations methods can be used to estimate in situ mechanical properties on a limited number of sites. On the other hand, this can be done on high stiffness materials (metals, glasses, ceramics...) by using acoustic microscopy. To apply this technique to wood, experimental procedure should be assessed. Trials on a scanning acoustic microscope show that for high resolution images, thin slices (~ 5 µm) after resin inclusion with water or potassium iodure as coupling liquid respectively at 600 MHz or 1 GHz give good results giving way to quantitative measurement of cell wall stiffness by image analysis.

Eperua falcata Aublet, best known under its vernacular name Wapa, represents more than 20%, in volume, of the potential wood production of the French guianian forest (its spatial repartition is aggregative). Its xylem has an excellent natural durability with good mechanical properties in relation to density (0,85). However, its use as a resource is very limited because the output of raw material is very uncertain. This is particulary affected by an important split risk when felling and deformation during sawing and drying, because of tension-wo

Eperua falcata (vernacular name 'Wapa') is an abundant species of the French Guianan forest. However, its wood is scarcely used because of high growth stresses. These growth stresses, as viewed by the wood technologist, are pre-stresses of green timber that are released during wood processing with unexpected splits and deformations. For the living tree, growth stresses are internal forces generated by wood differentiation that improve the mechanical strength and allow reorientations or stabilisations of unequilibrated (asymmetric) trees, when heterogeneous stresses, associated with tension wood, are generated. We studied the magnitude of growth stresses in relation with the tree morphology and especially its lean and asymmetry. For that, we measured residual strains at the stem periphery for at least 8 points of the circumference, at three heights (the bole base, 1.3 m and 3.3 m) of 10 trees (Yiyi forest, French Guiana). The measured strains are always tensile ones : wood in hardwoods is under longitudinal tension at the stem surface and this internal stress is higher than the bending (compressive or tensile) effects of gravity. The magnitude of residual strains is not related to the tree diameter (that is quite as expected) nor to the stem lean or the crown asymmetry. But high variations of growth stresses are related to the presence of buttresses that are more strongly prestressed in tension than the neighbouring wood, and therefore act mechanically as guy ropes. Moreover, these buttresses have no effects on wood located on higher parts of the stem, as the residual strains measured at 3.3 m are not related with other heights. Therefore, measurements of wood quality near the trunk base (for example, at the usual breast height) can give only poor information on the quality of the other parts of the stem. Furthermore, we found that when different imbalance factors as the slope and the crown asymmetry are considered, high values of residual strains are measured on buttresses (or sometimes on striations). This could be the expression of a reaction of the tree system of anchorage.

Eperua falcata Aubl. is the most common of the large tree species in the lowland rain-forest of Piste Saint Elie (French Guiana). One of these tall trees was felled for scientific purposes and found to have a bole hollowed throughout its entire length. This hollow trunk was filled with organic soil in which a complete adventitious root system had developped. This internal root system originated at the first fork (16 m above ground level) and penetrated the hollow trunk down to soil level through numerous fine roots. In this case the life span of the tree was probably increased, as its stability and its nutrition were improved by the extra roots. Such a situation is quite likely to be exceptional and due to accidental circumstances where both termites (or ants) and microorganisms played an important role., Foresta H. de,Kahn Francis. Un système racinaire adventif dans un tronc creux d'Eperua falcata Aubl. In: Revue d'Écologie (La Terre et La Vie), tome 39, n°3, 1984. pp. 347-350.