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Brémaud, I.; El Kaïm, Y.; Guibal, D.; Minato, K.; Thibaut, B.; Gril, J. |
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Characterisation and categorisation of the diversity in viscoelastic vibrational properties between 98 wood types |
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Journal Article |
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2012 |
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Annals of Forest Science |
Abbreviated Journal |
Ann. Forest Sci. |
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69 |
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3 |
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373-386 |
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Damping coefficient; Dynamic mechanical properties; Specific dynamic modulus of elasticity; Specific gravity; Viscoelastic vibrational properties; Wood diversity |
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· 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. |
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Wood Laboratory, EMPA, Überlandstrasse 129, 8600 Dübendorf, Switzerland |
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12864560 (Issn) |
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Export Date: 20 June 2012; Source: Scopus; Coden: Afosf; doi: 10.1007/s13595-011-0166-z; Language of Original Document: English; Correspondence Address: Brémaud, I.; Wood Laboratory, EMPA, Überlandstrasse 129, 8600 Dübendorf, Switzerland; email: iris_bremaud@hotmail.com |
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EcoFoG @ webmaster @ |
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403 |
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McLean, J.P.; Arnould, O.; Beauchene, J.; Clair, B. |
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The effect of the G-layer on the viscoelastic properties of tropical hardwoods |
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Journal Article |
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Year |
2012 |
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Annals of Forest Science |
Abbreviated Journal |
Ann. Forest Sci. |
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69 |
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3 |
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399-408 |
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Dma; G-layer; Reaction wood; Tropical wood; Viscoelasticity |
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· 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. |
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UMR Ecologie des Forêts de Guyane (ECOFOG), CIRAD, Kourou, French Guiana |
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12864560 (Issn) |
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Export Date: 20 June 2012; Source: Scopus; Coden: Afosf; doi: 10.1007/s13595-011-0164-1; Language of Original Document: English; Correspondence Address: McLean, J.P.; Forest Products Research Institute, Edinburgh Napier University, Merchiston Campus, Edinburgh EH10 5DT, United Kingdom; email: p.mclean@napier.ac.uk |
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Letort, V.; Heuret, P.; Zalamea, P.-C.; De Reffye, P.; Nicolini, E. |
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Analysing the effects of local environment on the source-sink balance of Cecropia sciadophylla: A methodological approach based on model inversion |
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2012 |
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Annals of Forest Science |
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Ann. Forest Sci. |
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69 |
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2 |
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167-180 |
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Cecropia; Functional-structural model; Model inversion; Morphology; Trophic competition |
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Context Functional-structural models (FSM) of tree growth have great potential in forestry, but their development, calibration and validation are hampered by the difficulty of collecting experimental data at organ scale for adult trees. Due to their simple architecture and morphological properties, “model plants” such as Cecropia sciadophylla are of great interest to validate new models and methodologies, since exhaustive descriptions of their plant structure and mass partitioning can be gathered. Aims Our objective was to develop a model-based approach to analysing the influence of environmental conditions on the dynamics of trophic competition within C. sciadophylla trees. Methods We defined an integrated environmental factor that includes meteorological medium-frequency variations and a relative index representing the local site conditions for each plant. This index is estimated based on model inversion of the GreenLab FSM using data from 11 trees for model calibration and 7 trees for model evaluation. Results The resulting model explained the dynamics of biomass allocation to different organs during the plant growth, according to the environmental pressure they experienced. Perspectives By linking the integrated environmental factor to a competition index, an extension of the model to the population level could be considered. © INRA and Springer Science+Business Media B.V. 2011. |
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UMR ECOFOG Campus Agronomique, INRA, BP 316, 97379 Kourou cedex, French Guiana |
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Cited By (since 1996): 1; Export Date: 20 June 2012; Source: Scopus; Coden: Afosf; doi: 10.1007/s13595-011-0131-x; Language of Original Document: English; Correspondence Address: Letort, V.; Department of Applied Mathematics and Systems (MAS), Ecole Centrale Paris, Grande voie des Vignes, Chatenay-Malabry 92295, France; email: veronique.letort@centraliens.net |
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EcoFoG @ webmaster @ |
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405 |
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Siebicke, L.; Hunner, M.; Foken, T. |
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Aspects of CO 2 advection measurements |
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2012 |
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Theoretical and Applied Climatology |
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Theor. Appl. Climatol. |
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109 |
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1-2 |
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109-131 |
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Observations of vegetation-atmosphere exchange of carbon dioxide (CO 2) by the eddy covariance (EC) technique are limited by difficult conditions such as nighttime and heterogeneous terrain. Thus, advective flux components are included into the net ecosystem exchange (NEE) budget. However, advection measurements are experimentally challenging and do not always help to solve the night flux problem of the EC technique. This study investigates alternative methods for the observation of horizontal advection, in particular horizontal concentration gradients, as well as different approaches to coordinate rotation and vertical advection. Continuous high-frequency measurements of the horizontal CO 2 concentration field are employed and compared to the often used discontinuous sequential sampling. Significant differences were found in the case of 30-min mean concentration values between the conventional discontinuous sampling approach and the complete observation of the time series by continuous sampling. Estimates of vertical advection rely on accurate estimates of vertical wind velocity (W). Therefore, different approaches to the planar fit coordinate rotation have been investigated. Sector-wise rotation was able to eliminate directional dependencies of mean W. Furthermore, the effect of the data set length used for rotation (window length) was investigated and was found to have significant impact on estimates of vertical advection, with larger window lengths yielding about 50% larger vertical advection. A sequential planar fit with controlled window length is proposed to give reproducible results. The different approaches to the measurement and calculation of horizontal and vertical advection presented are applied to data obtained during the exchange processes in mountainous region experiment at the FLUXNET site Waldstein-Weidenbrunnen (DE-Bay). Estimates of NEE including advection are compared to NEE from turbulent and storage flux alone without advection. NEE including vertical advection with sector-wise planar fit rotation and controlled window length and including horizontal advection from continuous gradient measurements, which were comprehensively bias corrected by a new approach, did compare well with the expected night flux error, with meteorological drivers of the fluxes and with soil chamber measurements. Unrealistically large and noisy values of horizontal advection from the conventional discontinuous sampling approach, which lead to unrealistic values of NEE, could be eliminated by the alternative approaches presented. We therefore suggest the further testing of those approaches at other sites in order to improve the accuracy of advection measurements and, subsequently, estimates of NEE. © 2011 Springer-Verlag. |
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Wind Cert Services, TÜV SÜD Industrie Service GmbH, Ludwig-Eckert-Str. 10, 93049 Regensburg, Germany |
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0177798x (Issn) |
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Export Date: 27 June 2012; Source: Scopus; doi: 10.1007/s00704-011-0552-3; Language of Original Document: English; Correspondence Address: Siebicke, L.; Department of Micrometeorology, University of Bayreuth, Universitätsstr. 30, 95440 Bayreuth, Germany; email: lukas.siebicke@uni-bayreuth.de |
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Coq, S.; Weigel, J.; Bonal, D.; Hattenschwiler, S. |
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Litter mixture effects on tropical tree seedling growth – a greenhouse experiment |
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2012 |
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Plant Biology |
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Plant Biol. |
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14 |
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4 |
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630-640 |
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Amazonian lowland rain forest; Autotoxicity; Belowground/aboveground interactions; Litter decomposition; Plant nutrition; Plant-soil feedback |
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Decomposing litter provides critical nutrients for plants, particularly in nutrient-poor ecosystems such as tropical forests. We hypothesised that decomposing litter improves the performance of a variety of tropical tree seedlings, and that this litter effect varies depending on the species of litter present in litter mixtures. We addressed these hypotheses with a large pot experiment manipulating a range of different litter mixtures of contrasting quality and using seedlings of four tree species from the Amazonian forest of French Guiana. In contrast to our initial hypothesis, decomposing litter had either neutral or negative impacts on seedling growth, despite strongly different growth rates, biomass allocation patterns and leaf and root traits among tree species. Tree species varied in their responses to litter additions, which were further modified by species identity of the added litter. Our data show litter species-specific effects on growth, biomass allocation and leaf and root traits of tropical tree seedlings. These results suggest that a net nutrient release from decomposing litter does not necessarily improve tree seedling growth, even under nutrient-limiting conditions. In conclusion, litter layer composition may affect seedling establishment and recruitment success beyond litter-derived plant nutrient availability, which may contribute to tree species composition and dynamics in the studied tropical forest. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands. |
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INRA, UMR, Écologie et Écophysiologie, Champenoux, France |
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Export Date: 27 June 2012; Source: Scopus; Coden: Pbiof; doi: 10.1111/j.1438-8677.2011.00534.x; Language of Original Document: English; Correspondence Address: Coq, S.; Laboratoire d'Ecologie Alpine (LECA), CNRS, Université Joseph Fourier, BP 53, F-38042 Grenoble, Cedex 09, France; email: sylvain.coq@gmail.com |
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Rey, O.; Estoup, A.; Vonshak, M.; Loiseau, A.; Blanchet, S.; Calcaterra, L.; Chifflet, L.; Rossi, J.-P.; Kergoat, G.J.; Foucaud, J.; Orivel, J.; Leponce, M.; Schultz, T.; Facon, B. |
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Where do adaptive shifts occur during invasion? A multidisciplinary approach to unravelling cold adaptation in a tropical ant species invading the Mediterranean area |
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2012 |
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Ecology Letters |
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Ecol. Lett. |
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15 |
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11 |
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1266-1275 |
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Adaptation; Biological invasion; Climatic niche shift; Cold temperature; Mediterranean zone; Wasmannia auropunctata |
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Evolution may improve the invasiveness of populations, but it often remains unclear whether key adaptation events occur after introduction into the recipient habitat (i.e. post-introduction adaptation scenario), or before introduction within the native range (i.e. prior-adaptation scenario) or at a primary site of invasion (i.e. bridgehead scenario). We used a multidisciplinary approach to determine which of these three scenarios underlies the invasion of the tropical ant Wasmannia auropunctata in a Mediterranean region (i.e. Israel). Species distribution models (SDM), phylogeographical analyses at a broad geographical scale and laboratory experiments on appropriate native and invasive populations indicated that Israeli populations followed an invasion scenario in which adaptation to cold occurred at the southern limit of the native range before dispersal to Israel. We discuss the usefulness of combining SDM, genetic and experimental approaches for unambiguous determination of eco-evolutionary invasion scenarios. © 2012 Blackwell Publishing Ltd/CNRS. |
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Smithsonian Institute, Department of Entomology, Natural Museum of Natural History, Washington, DC, 20013, United States |
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1461023x (Issn) |
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Export Date: 19 October 2012; Source: Scopus; Coden: Eclef; doi: 10.1111/j.1461-0248.2012.01849.x; Language of Original Document: English; Correspondence Address: Rey, O.; INRA, UMR1062, CBGP, Montpellier, France; email: olivier.rey.1@gmail.com |
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441 |
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Coté, G.G.; Gibernau, M. |
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Distribution of calcium oxalate crystals in floral organs of araceae in relation to pollination strategy |
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2012 |
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American Journal of Botany |
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Am. J. Bot. |
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99 |
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7 |
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1231-1242 |
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Araceae; Beetles; Calcium oxalate; Crystal; Defense; Flowers; Herbivory; Pollination |
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Premise of the study: Many flowers are pollinated by potentially hungry insects, yet flowers also contain gametes and embryos which must be protected from predation. Microscopic calcium oxalate crystals in plant tissues have been proposed to protect against herbivory. Aroids, which have an unusual diversity of such crystals, also exhibit diverse pollination strategies. Many species have pollinators that do not feed while visiting the flowers, while other species, especially those pollinated by beetles, offer sterile staminodia as food rewards. We examined flowers of 21 aroid species with various pollination strategies to test the hypothesis that crystals protect vital gametes and embryos while allowing consumption of food bribes.Methods: Aroid inflorescences collected from the field or from greenhouse material were sectioned, cleared, and examined by bright field and polarization microscopy.Key results: All species examined, regardless of pollination strategy, arrayed crystals around unshed pollen and ovules. Less vital tissues, such as odoriferous appendages, had few crystals. Staminodia offered as food to beetle pollinators, however, differed greatly between species in their crystal contents. Some had minimal crystals; some had crystals in patterns suggesting they limit beetle feeding; still others had abundant crystals in no obvious pattern.Conclusions: The results are consistent with crystals protecting against insect predation of gametes and embryos. However, the role of crystals in food-bribe staminodia is unclear. They may limit and direct feeding by beetles in some species, while in others they might have no protective role. © 2012 Botanical Society of America. |
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CNRS-Ecolog (UMR 8172), Campus Agronomique BP316, Korou cedex 97379, France |
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Export Date: 10 August 2012; Source: Scopus; Coden: Ajboa; doi: 10.3732/ajb.1100499; Language of Original Document: English; Correspondence Address: Coté, G. G.; Biology Department, Radford University, Radford, VA 24142-6931, United States; email: gcote@radford.edu |
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420 |
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Salvin, P.; Roos, C.; Robert, F. |
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Tropical mangrove sediments as a natural inoculum for efficient electroactive biofilms |
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2012 |
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Bioresource Technology |
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Bioresour. Technol. |
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120 |
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45-51 |
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Chronoamperometry; Cyclic voltammetry; Electroactive biofilms; Microbial fuel cells; Three-electrode systems |
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Chronoamperometry is known to be an efficient way to form electroactive biofilms (EAB) on conductive electrodes. For the first time, tropical mangrove sediments are analyzed as a potential inoculum to form MFC anodes with the use of acetate as substrate. The performance of the EAB-coated carbon cloth electrodes are evaluated according to the maximal current density, the coulombic efficiency and the cyclic voltammogramms. Working electrodes (WE) polarized at -0.2V/SCE gave better results compared to -0.4V/SCE and 0.0V/SCE. The maximal current density attained was 12A/m 2 with a CE of 24%. Contributions of the EAB in the generation of current were discussed and mechanisms of electronic transfer by the bacteria were discussed. Epifluorescence and SEM images showed the evolution of the biofilms on the electrode surface and the heterogeneity of the structure. © 2012 Elsevier Ltd. |
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Laboratoire des Matériaux et des Molécules en Milieu Amazonien, Université des Antilles et de la Guyane, UAG-UMR ECOFOG, F-97337 Cayenne, French Guiana |
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09608524 (Issn) |
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Export Date: 16 August 2012; Source: Scopus; Coden: Birte; doi: 10.1016/j.biortech.2012.05.131; Language of Original Document: English; Correspondence Address: Robert, F.; Laboratoire des Matériaux et des Molécules en Milieu Amazonien, Université des Antilles et de la Guyane, UAG-UMR ECOFOG, F-97337 Cayenne, French Guiana; email: florent.robert@guyane.univ-ag.fr |
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EcoFoG @ webmaster @ |
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421 |
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Soudani, K.; Hmimina, G.; Delpierre, N.; Pontailler, J.-Y.; Aubinet, M.; Bonal, D.; Caquet, B.; de Grandcourt, A.; Burban, B.; Flechard, C.; Guyon, D.; Granier, A.; Gross, P.; Heinesh, B.; Longdoz, B.; Loustau, D.; Moureaux, C.; Ourcival, J.-M.; Rambal, S.; Saint André, L.; Dufrêne, E. |
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Ground-based Network of NDVI measurements for tracking temporal dynamics of canopy structure and vegetation phenology in different biomes |
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2012 |
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Remote Sensing of Environment |
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Remote Sens. Environ. |
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123 |
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234-245 |
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Crops; Evergreen and deciduous forests; Ground-based NDVI; Herbaceous savanna; NDVI time-series; Phenology; Tropical rain forest |
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Plant phenology characterises the seasonal cyclicity of biological events such as budburst, flowering, fructification, leaf senescence and leaf fall. These biological events are genetically pre-determined but also strongly modulated by climatic conditions, particularly temperature, daylength and water availability. Therefore, the timing of these events is considered as a good indicator of climate change impacts and as a key parameter for understanding and modelling vegetation-climate interactions. In situ observations, empirical or bioclimatic models and remotely sensed time-series data constitute the three possible ways for monitoring the timing of plant phenological events. Remote sensing has the advantage of being the only way of surface sampling at high temporal frequency and, in the case of satellite-based remote sensing, over large regions. Nevertheless, exogenous factors, particularly atmospheric conditions, lead to some uncertainties on the seasonal course of surface reflectance and cause bias in the identification of vegetation phenological events. Since 2005, a network of forest and herbaceous sites has been equipped with laboratory made NDVI sensors to monitor the temporal dynamics of canopy structure and phenology at an intra-daily time step. In this study, we present recent results obtained in several contrasting biomes in France, French Guiana, Belgium and Congo. These sites represent a gradient of vegetation ecosystems: the main evergreen and deciduous forest ecosystems in temperate climate region, an evergreen tropical rain forest in French Guiana, an herbaceous savanna ecosystem in Congo, and a succession of three annual crops in Belgium. In this paper, (1) we provide an accurate description of the seasonal dynamics of vegetation cover in these different ecosystems (2) we identify the most relevant remotely sensed markers from NDVI time-series for determining the dates of the main phenological events that characterize these ecosystems and (3) we discuss the relationships between temporal canopy dynamics and climate factors. In addition to its importance for phenological studies, this ground-based Network of NDVI measurement provides data needed for the calibration and direct validation of satellite observations and products. © 2012 Elsevier Inc. |
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INRA, Unité Biogéochimie des Ecosystèmes Forestiers, Champenoux, France |
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Export Date: 16 August 2012; Source: Scopus; Coden: Rseea; doi: 10.1016/j.rse.2012.03.012; Language of Original Document: English; Correspondence Address: Soudani, K.; University of Paris-Sud, CNRS, AgroParisTech, Laboratoire Ecologie Systematique et Evolution, Faculty of Sciences of OrsayFrance; email: kamel.soudani@u-psud.fr |
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EcoFoG @ webmaster @ |
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422 |
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Fromin, N.; Porte, B.; Lensi, R.; Hamelin, J.; Domenach, A.-M.; Buatois, B.; Roggy, J.-C. |
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Spatial variability of the functional stability of microbial respiration process: A microcosm study using tropical forest soil |
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2012 |
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Journal of Soils and Sediments |
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J. Soils Sed. |
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12 |
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7 |
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1030-1039 |
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Disturbance; Diversity-stability relationship; Microbial diversity; Substrate-induced respiration |
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Purpose: Understanding the ability of ecosystem processes to resist to and to recover from disturbances is critical to sustainable land use. However, the spatial variability of the stability has rarely been addressed. Here, we investigated the functional stability of a soil microbial process for 24 soils collected from adjacent locations from a 0. 3 ha tropical rainforest plot in Paracou, French Guiana. Materials and methods: The 24 locations were characterized regarding soil chemical and biological (microbial diversity) parameters and forest structure. The corresponding soils were submitted to an experimental transient heat disturbance during a microcosm experiment. The response of the respiration process was followed using substrate-induced respiration (SIR). Results and discussion: The response of soil SIR to heat disturbance varied widely between samples. The variability of the SIR response increased just after the disturbance, and a global rather homogeneous decrease in SIR rates was observed 15 and 30 days after. The stability of SIR in response to heat disturbance could not be related to either the genetic or the metabolic diversity of the microbial community. The initial level of SIR before the disturbance was the soil variable that best correlated with the impact of the disturbance: the soil locations with the highest initial SIR rates were the most affected 15 and 30 days after the heat disturbance. Conclusions: Such a heterogeneous response suggests that the response of soil processes to a disturbance will be difficult to assess from only local-scale analyses and highlights the need for spatial explicitness in understanding biogeochemical processes. © 2012 Springer-Verlag. |
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UMR EcoFoG, BP 709, 97387 Kourou, French Guiana |
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Export Date: 30 July 2012; Source: Scopus; doi: 10.1007/s11368-012-0528-7; Language of Original Document: English; Correspondence Address: Fromin, N.; CEFE, CNRS UMR 5175, 1919 Route de Mende, 34293 Montpellier cedex 5, France; email: nathalie.fromin@cefe.cnrs.fr |
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