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Niamké, F. B., Amusant, N., Kadio, A. A., Thevenon, M. - F., Nourissier, S., Adima, A. A., et al. (2014). Rapid prediction of phenolic compounds as chemical markers for the natural durability of teak (Tectona grandis Linn f.) heartwood by near infrared spectroscopy. J. Near Infrared Spectrosc., 22(1), 35–43.
Abstract: Near infrared (NIR) spectroscopy provides rapid and non-destructive analysis of wood properties and composition. In this study, we aimed to use NIR measurement for the prediction of teak phenolic compounds, which are chemical markers for natural durability of wood. Twenty-seven teak trees from two geographical zones (Malaysia and Ivory Coast) were used. On ground heartwood samples, the content of total phenolics and individual quinones (tectoquinone, 2-(hydroxymethyl)anthraquinone, 2-anthraquinone carboxylic acid, 1,4-naphthoquinoneand 4c,5c-dihydroxy-epiisocatalponol) were determined using high performance liquid chromatography (HPLC). Partial least squares (PLS) regression with NIR spectra on the same samples and phenolic data was used to build NIR models for phenolic contents. The PLS models for the total predicted phenolics and three quinone contents (tectoquinone, 2-(hydroxymethyl) anthraquinone, and 4¢,5¢-dihydroxy-epiisocatalponol) showed a good ratio of performance to deviation (RPD ≥ 2.5), strong coefficients of determination (r2 ≥ 0.8) and the prediction errors were consistent with the reference method. These results demonstrate that NIR spectroscopy can be reliable for the evaluation of total phenolics and individual quinones in teak heartwood wood meal. NIR spectroscopy is a promising technique for rapidly providing information on the quinone contents in teak wood and indirectly for knowing its natural durability. This finding leads to a precise, non-destructive tool for teak wood quality evaluation. © IM Publications LLP 2014.
Keywords: Heartwood; Hplc; Natural durability; NIR spectroscopy; Phenolic; Prediction; Quinone; Tectona grandis
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Brémaud, I., El Kaïm, Y., Guibal, D., Minato, K., Thibaut, B., & Gril, J. (2012). Characterisation and categorisation of the diversity in viscoelastic vibrational properties between 98 wood types. Ann. Forest Sci., 69(3), 373–386.
Abstract: · Context Increased knowledge on diversity in wood properties would have implications both for fundamental research and for promoting a diversification of uses as material. · Aims The objective is to contribute to overcoming the critical lack of data on the diversity of wood dynamic mechanical/viscoelastic vibrational properties by testing lesser known species and categorising sources of variability. · Methods Air-dry axial specific dynamic modulus of elasticity (E′/γ) and damping coefficient (tand) were measured on a wide sampling (1,792 specimens) of 98 wood types from 79 species. An experimental device and protocol was designed for conducting systematic (i.e. rapid and reproducible) characterisations. · Results Diversity at the specimens' level corroborates the “standard” relationship between tanδ and E'/γ, which is discussed in terms of orientation of wood elements and of chemical composition. Diversity at the species level is expressed on the basis of results for normal heartwood, with specific gravity (γ) ranging from 0.2 to 1.3. Axial E'/γ ranges from 9 to 32 GPa and tand from 4×10 -3 to 19×10 -3. Properties distribution follows a continuum, but with group characteristics. The lowest values of tanδ are only found in certain tropical hardwoods. Results can also suggest alternative species for musical instruments making. · Conclusion The variations in specific gravity, in stiffness or in “viscosity” appear to be predominantly linked to different levels of diversity: between species or between wood types (reaction wood or taxonomy-related differences in heartwood extractives). © INRA/Springer-Verlag France 2011.
Keywords: Damping coefficient; Dynamic mechanical properties; Specific dynamic modulus of elasticity; Specific gravity; Viscoelastic vibrational properties; Wood diversity
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McLean, J. P., Arnould, O., Beauchene, J., & Clair, B. (2012). The effect of the G-layer on the viscoelastic properties of tropical hardwoods. Ann. Forest Sci., 69(3), 399–408.
Abstract: · Context and aim This study aimed to examine the effect of the tension wood G-layer on the viscoelastic properties of wood. · Methods Tension wood and opposite wood samples were obtained from six French Guianese tropical rainforest species (Sextonia rubra, Ocotea guyanensis, Inga alba, Tachigali melinoni, Iyranthera sagotiana and Virola michelii); the tension wood of the former three of these species had a Glayer, whilst the tension wood from the latter three had no Glayer. Tensile dynamic mechanical analysis (DMA) was performed on green never dried wood samples in the longitudinal direction with samples submerged in a water bath at a temperature (30°C) and frequency (1 Hz) representative of the conditions experienced by wood within a living tree. Then, DMA was repeated with samples conditioned to an air-dried state. Finally, samples were oven-dried to measure longitudinal shrinkage. · Results Tension wood did not always have a higher longitudinal storage (elastic) modulus than opposite wood from the same tree regardless of the presence or absence of a G-layer. For the species containing a G-layer, tension wood had a higher damping coefficient and experienced a greater longitudinal shrinkage upon drying than opposite wood from the same species. No difference was found in damping coefficients between tension wood and opposite wood for the species that had no G-layer. · Conclusion It is proposed that the different molecular composition of the G-layer matrix has an influence on the viscoelasticity of wood, even if a biomechanical gain is not yet clear. This study shows that rheological properties and longitudinal shrinkage can be used to detect the presence of a G-layer in tension wood. © INRA/Springer-Verlag France 2011.
Keywords: Dma; G-layer; Reaction wood; Tropical wood; Viscoelasticity
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Phillips, O. L., Brienen, R. J. W., Gloor, E., Baker, T. R., Lloyd, J., Lopez-Gonzalez, G., et al. (2017). Carbon uptake by mature Amazon forests has mitigated Amazon nations' carbon emissions. Carbon Balance and Management, 12(1).
Abstract: Background: Several independent lines of evidence suggest that Amazon forests have provided a significant carbon sink service, and also that the Amazon carbon sink in intact, mature forests may now be threatened as a result of different processes. There has however been no work done to quantify non-land-use-change forest carbon fluxes on a national basis within Amazonia, or to place these national fluxes and their possible changes in the context of the major anthropogenic carbon fluxes in the region. Here we present a first attempt to interpret results from ground-based monitoring of mature forest carbon fluxes in a biogeographically, politically, and temporally differentiated way. Specifically, using results from a large long-term network of forest plots, we estimate the Amazon biomass carbon balance over the last three decades for the different regions and nine nations of Amazonia, and evaluate the magnitude and trajectory of these differentiated balances in relation to major national anthropogenic carbon emissions. Results: The sink of carbon into mature forests has been remarkably geographically ubiquitous across Amazonia, being substantial and persistent in each of the five biogeographic regions within Amazonia. Between 1980 and 2010, it has more than mitigated the fossil fuel emissions of every single national economy, except that of Venezuela. For most nations (Bolivia, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname) the sink has probably additionally mitigated all anthropogenic carbon emissions due to Amazon deforestation and other land use change. While the sink has weakened in some regions since 2000, our analysis suggests that Amazon nations which are able to conserve large areas of natural and semi-natural landscape still contribute globally-significant carbon sequestration. Conclusions: Mature forests across all of Amazonia have contributed significantly to mitigating climate change for decades. Yet Amazon nations have not directly benefited from providing this global scale ecosystem service. We suggest that better monitoring and reporting of the carbon fluxes within mature forests, and understanding the drivers of changes in their balance, must become national, as well as international, priorities. © 2017 The Author(s).
Keywords: Amazonia; Carbon balance; Carbon sink; Climate change; Ecosystem service; Land use change; Sequestration; Tropical forests
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Touchard, A., Aili, S. R., Téné, N., Barassé, V., Klopp, C., Dejean, A., et al. (2020). Venom Peptide Repertoire of the European Myrmicine Ant Manica rubida: Identification of Insecticidal Toxins. J. Proteome Res., 19(4), 1800–1811.
Abstract: Using an integrated transcriptomic and proteomic approach, we characterized the venom peptidome of the European red ant, Manica rubida. We identified 13 “myrmicitoxins” that share sequence similarities with previously identified ant venom peptides, one of them being identified as an EGF-like toxin likely resulting from a threonine residue modified by O-fucosylation. Furthermore, we conducted insecticidal assays of reversed-phase HPLC venom fractions on the blowfly Lucilia caesar, permitting us to identify six myrmicitoxins (i.e., U3-, U10-, U13-, U20-MYRTX-Mri1a, U10-MYRTX-Mri1b, and U10-MYRTX-Mri1c) with an insecticidal activity. Chemically synthesized U10-MYRTX-Mri1a, -Mri1b, -Mri1c, and U20-MYRTX-Mri1a irreversibly paralyzed blowflies at the highest doses tested (30-125 nmol·g-1). U13-MYRTX-Mri1a, the most potent neurotoxic peptide at 1 h, had reversible effects after 24 h (150 nmol·g-1). Finally, U3-MYRTX-Mri1a has no insecticidal activity, even at up to 55 nmol·g-1. Thus, M. rubida employs a paralytic venom rich in linear insecticidal peptides, which likely act by disrupting cell membranes.
Keywords: glycosylated toxin; peptidome; polycationic α-helix; predation; pyroglutamate; reversible neurotoxicity
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Morel, H., Lehnebach, R., Cigna, J., Ruelle, J., Nicolini, É., & Beauchene, J. (2018). Basic wood density variations of Parkia velutina Benoist, a long-lived heliophilic Neotropical rainforest tree. Bois et Forets des Tropiques, 335, 59–69.
Abstract: Investigations of basic radial wood density (WD) in tropical trees revealed linear patterns and some curvilinear patterns. Studies usually disregard longitudinal variations, which are often considered to be similar to radial variations. This study aimed to show (1) a new radial curvilinear WD pattern, (2) differences in amplitude between radial and longitudinal gradients and (3) to partition WD variations according to different scales in Parkia velutina, an emergent tree found in Neotropical rain forests. We collected full discs from six felled trees and radial cores from 10 standing trees to check WD variability, plus one dominant axis per tree for analysis of height growth rates. This species showed very high growth rates indicative of heliophilic habits. WD varied from 0.194 to 0.642 g/cm3. Such amplitude is rarely observed within the same tree. Radial variation in WD was curvilinear, with an amplitude generally less than the longitudinal amplitude. Consequently, in mature trees, WD values in the crown were higher than those in the outer trunk. WD variations can be highly significant at different scales. The variance partitioning also revealed that the whole WD range of Parkia velutina is more accurately estimated intra-individually when both longitudinal and radial gradient are covered.
Keywords: Curvilinear pattern; French Guiana; Intra-tree; Tropical species
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Hartke, J., Sprenger, P. P., Sahm, J., Winterberg, H., Orivel, J., Baur, H., et al. (2019). Cuticular hydrocarbons as potential mediators of cryptic species divergence in a mutualistic ant association. Ecology and Evolution, 9(16), 9160–9176.
Abstract: Upon advances in sequencing techniques, more and more morphologically identical organisms are identified as cryptic species. Often, mutualistic interactions are proposed as drivers of diversification. Species of the neotropical parabiotic ant association between Crematogaster levior and Camponotus femoratus are known for highly diverse cuticular hydrocarbon (CHC) profiles, which in insects serve as desiccation barrier but also as communication cues. In the present study, we investigated the association of the ants’ CHC profiles with genotypes and morphological traits, and discovered cryptic species pairs in both genera. To assess putative niche differentiation between the cryptic species, we conducted an environmental association study that included various climate variables, canopy cover, and mutualistic plant species. Although mostly sympatric, the two Camponotus species seem to prefer different climate niches. However in the two Crematogaster species, we could not detect any differences in niche preference. The strong differentiation in the CHC profiles may thus suggest a possible role during speciation itself either by inducing assortative mating or by reinforcing sexual selection after the speciation event. We did not detect any further niche differences in the environmental parameters tested. Thus, it remains open how the cryptic species avoid competitive exclusion, with scope for further investigations. © 2019 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.
Keywords: environmental association; integrative taxonomy; niche differentiation; population structure; sexual selection; speciation
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Lambs, L., Bompy, F., & Dulormne, M. (2018). Using an “isotopic spike” from a tropical storm to understand water exchange on a large scale: Case study of Hurricane Rafael in the lesser antilles archipelago, October 2012. Rapid Communications in Mass Spectrometry, 32(6), 457–468.
Abstract: Rationale: Studies of wetland eco-hydrology in tropical coastal areas are scarce, and the use of water stable isotopes can be of great help. Key constraints for their analysis are (i) the small difference in delta18O values between seawater and old evaporated freshwater, and (ii) the fact that the presence of old brackish water limits the determination of the water origin and dynamic. Methods: The water from tropical storms displays distinctively depleted heavy stable isotopes, in comparison with usual tropical rainfall without strong convective thunderstorms. During tropical storms, such as Hurricane Rafael in mid-October 2012, the rainfall delta18O signal can be decreased by many units. This effect is called an “isotopic spike”, and it could be used as a temporal marker of the water fluxes. Results: Water samples, with delta18O values as low as −8.9/1000, were collected on the islands of Guadeloupe and Saint-Martin during Hurricane Rafael, whereas the usual range of groundwater or mean rainfall delta18O values is around −2.8 +/- 0.5 /1000, as measured from 2009 to 2012. These water “isotopic spikes” allow us to show a surface freshwater uptake by mangrove trees in Guadeloupe, and in Saint-Martin, to calculate the water renewal of the salt ponds and pools. Conclusions: The “isotopic spikes” generated by tropical storms are generally used to track back past storm events, as recorded in trees and stalagmites. Here, the propagation of isotopic spike is followed to improve the understanding of the freshwater circulation and the water dynamic within coastal ecosystems influenced by seawater.
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Torroba-Balmori, P., Budde, K. B., Heer, K., González-Martínez, S. C., Olsson, S., Scotti-Saintagne, C., et al. (2017). Altitudinal gradients, biogeographic history and microhabitat adaptation affect fine-scale spatial genetic structure in African and Neotropical populations of an ancient tropical tree species. PLoS ONE, 12(8), e0182515.
Abstract: The analysis of fine-scale spatial genetic structure (FSGS) within populations can provide insights into eco-evolutionary processes. Restricted dispersal and locally occurring genetic drift are the primary causes for FSGS at equilibrium, as described in the isolation by distance (IBD) model. Beyond IBD expectations, spatial, environmental or historical factors can affect FSGS. We examined FSGS in seven African and Neotropical populations of the late-successional rain forest tree Symphonia globulifera L. f. (Clusiaceae) to discriminate the influence of drift-dispersal vs. landscape/ecological features and historical processes on FSGS. We used spatial principal component analysis and Bayesian clustering to assess spatial genetic heterogeneity at SSRs and examined its association with plastid DNA and habitat features. African populations (from Cameroon and São Tomé) displayed a stronger FSGS than Neotropical populations at both marker types (mean Sp = 0.025 vs. Sp = 0.008 at SSRs) and had a stronger spatial genetic heterogeneity. All three African populations occurred in pronounced altitudinal gradients, possibly restricting animal-mediated seed dispersal. Cyto-nuclear disequilibria in Cameroonian populations also suggested a legacy of biogeographic history to explain these genetic patterns. Conversely, Neotropical populations exhibited a weaker FSGS, which may reflect more efficient wide-ranging seed dispersal by Neotropical bats and other dispersers. The population from French Guiana displayed an association of plastid haplotypes with two morphotypes characterized by differential habitat preferences. Our results highlight the importance of the microenvironment for eco-evolutionary processes within persistent tropical tree populations. © 2017 Torroba-Balmori et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Ghislain, B., & Clair, B. (2017). Diversity in the organisation and lignification of tension wood fibre walls – A review. IAWA Journal, 38(2), 245–265.
Abstract: Tension wood, a tissue developed by angiosperm trees to actively recover their verticality, has long been defined by the presence of an unlignified cellulosic inner layer in the cell wall of fibres, called the G-layer. Although it was known that some species have no G-layer, the definition was appropriate since it enabled easy detection of tension wood zones using various staining techniques for either cellulose or lignin. For several years now, irrespective of its anatomical structure, tension wood has been defined by its high mechanical internal tensile stress. This definition enables screening of the diversity of cell walls in tension wood fibres. Recent results obtained in tropical species with tension wood with a delay in the lignification of the G-layer opened our eyes to the effective presence of large amounts of lignin in the G-layer of some species. This led us to review older literature mentioning the presence of lignin deposits in the G-layer and give them credit. Advances in the knowledge of tension wood fibres allow us to reconsider some previous classifications of the diversity in the organisation of the fibre walls of the tension wood. © 2017 International Association of Wood Anatomists.
Keywords: diversity; fibres; G-layer; lignification; multilayered tension wood fibre walls; S1 + S2 + S3 + G; Tension wood
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