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Dejean, A., Petitclerc, F., Azémar, F., Pélozuelo, L., Talaga, S., Leponce, M., et al. (2018). Aquatic life in Neotropical rainforest canopies: Techniques using artificial phytotelmata to study the invertebrate communities inhabiting therein. Comptes Rendus – Biologies, 341(1), 20–27.
Abstract: In Neotropical rainforest canopies, phytotelmata (“plant-held waters”) shelter diverse aquatic macroinvertebrate communities, including vectors of animal diseases. Studying these communities is difficult because phytotelmata are widely dispersed, hard to find from the ground and often inaccessible. We propose here a method for placing in tree crowns “artificial phytotelmata” whose size and shape can be tailored to different research targets. The efficacy of this method was shown while comparing the patterns of community diversity of three forest formations. We noted a difference between a riparian forest and a rainforest, whereas trees alongside a dirt road cutting through that rainforest corresponded to a subset of the latter. Because rarefied species richness was significantly lower when the phytotelmata were left for three weeks rather than for six or nine weeks, we recommend leaving the phytotelmata for twelve weeks to permit predators and phoretic species to fully establish themselves.
Keywords: Artificial phytotelmata; Epiphytes; French Guiana; Invertebrate diversity; Neotropical rainforests
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Hmimina, G., Dufrêne, E., Pontailler, J. - Y., Delpierre, N., Aubinet, M., Caquet, B., et al. (2013). Evaluation of the potential of MODIS satellite data to predict vegetation phenology in different biomes: An investigation using ground-based NDVI measurements. Remote Sensing of Environment, 132, 145–158.
Abstract: Vegetation phenology is the study of the timing of seasonal events that are considered to be the result of adaptive responses to climate variations on short and long time scales. In the field of remote sensing of vegetation phenology, phenological metrics are derived from time series of optical data. For that purpose, considerable effort has been specifically focused on developing noise reduction and cloud-contaminated data removal techniques to improve the quality of remotely-sensed time series. Comparative studies between time series composed of satellite data acquired under clear and cloudy conditions and from radiometric data obtained with high accuracy from ground-based measurements constitute a direct and effective way to assess the operational use and limitations of remote sensing for predicting the main plant phenological events. In the present paper, we sought to explicitly evaluate the potential use of MODerate resolution Imaging Spectroradiometer (MODIS) remote sensing data for monitoring the seasonal dynamics of different types of vegetation cover that are representative of the major terrestrial biomes, including temperate deciduous forests, evergreen forests, African savannah, and crops. After cloud screening and filtering, we compared the temporal patterns and phenological metrics derived from in situ NDVI time series and from MODIS daily and 16-composite products. We also evaluated the effects of residual noise and the influence of data gaps in MODIS NDVI time series on the identification of the most relevant metrics for vegetation phenology monitoring. The results show that the inflexion points of a model fitted to a MODIS NDVI time series allow accurate estimates of the onset of greenness in the spring and the onset of yellowing in the autumn in deciduous forests (RMSE ≤ one week). Phenological metrics identical to those provided with the MODIS Global Vegetation Phenology product (MDC12Q2) are less robust to data gaps, and they can be subject to large biases of approximately two weeks or more during the autumn phenological transitions. In the evergreen forests, in situ NDVI time series describe the phenology with high fidelity despite small temporal changes in the canopy foliage. However, MODIS is unable to provide consistent phenological patterns. In crops and savannah, MODIS NDVI time series reproduce the general temporal patterns of phenology, but significant discrepancies appear between MODIS and ground-based NDVI time series during very localized periods of time depending on the weather conditions and spatial heterogeneity within the MODIS pixel. In the rainforest, the temporal pattern exhibited by a MODIS 16-day composite NDVI time series is more likely due to a pattern of noise in the NDVI data structure according to both rainy and dry seasons rather than to phenological changes. More investigations are needed, but in all cases, this result leads us to conclude that MODIS time series in tropical rainforests should be interpreted with great caution. © 2013 Elsevier Inc.
Keywords: Crops; Deciduous forests; Evergreen forests; Ground-based NDVI; Modis; Phenology
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Royer, M., Stien, D., Beauchene, J., Herbette, G., McLean, J. P., Thibaut, A., et al. (2010). Extractives of the tropical wood wallaba (Eperua falcata Aubl.) as natural anti-swelling agents. Holzforschung, 64(2), 211–215.
Abstract: Wallaba (Eperua falcata) is a tropical wood that is known to have naturally high moisture related dimensional stability. Samples of wallaba heartwood were subjected to differential solvent extraction. Wood pieces that were extracted with methanol showed significantly greater swelling following rehydration from oven dry to 96% relative humidity than non- extracted samples and samples extracted with other solvents. Methanol soluble wallaba heartwood extract was purified by HPLC and the compounds present were characterized by NMR spectroscopy. The structure of 13 compounds in methanol extract was identified. The relative proportion of polar compounds in methanol extract was found to be high. The compounds identified are proposed to bind to the polymeric cell wall by means of multiple hydrogen bonds restricting the association of water and therefore act as natural anti-swelling agents.
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Boisse, P., Aimene, Y., Dogui, A., Dridi, S., Gatouillat, S., Hamila, N., et al. (2010). Hypoelastic, hyperelastic, discrete and semi-discrete approaches for textile composite reinforcement forming. International Journal of Material Forming, 3(Supplement 2), 1229–1240.
Abstract: The clear multi-scale structure of composite textile reinforcements leads to develop continuous and discrete approaches for their forming simulations. In this paper two continuous modelling respectively based on a hypoelastic and hyperelastic constitutive model are presented. A discrete approach is also considered in which each yarn is modelled by shell finite elements and where the contact with friction and possible sliding between the yarns are taken into account. Finally the semi-discrete approach is presented in which the shell finite element interpolation involves continuity of the displacement field but where the internal virtual work is obtained as the sum of tension, in-plane shear and bending ones of all the woven unit cells within the element. The advantages and drawbacks of the different approaches are discussed.
Keywords: Textile composites Forming simulations Continuous/discrete approaches Hyperelasticity Hypoelasticity Semi-discrete finite element
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Vedel, V., & Arthur, W. (2009). Character changes during the early post-embryonic development of the centipede Strigamia maritima (Leach, 1817) (Chilopoda: Geophilomorpha). International Journal of Myriapodology, 2(1), 53–61.
Abstract: For many kinds of ecological, evolutionary and developmental study, it is important to be able to describe the life-history of the individuals of a particular species/population. In the case of myriapods and other arthropods, this involves separating the different life-history stages (or stadia or instars) that are separated by moults. However, it has recently been pointed out that in the earliest post-embryonic stages the cuticle is still quite flexible; this means that visible external developmental changes can occur between moults as well as during them. Here, we provide evidence for such inter-moult changes in the coastal geophilomorph centipede Strigamia maritima. The character states studied enable finer-scale resolution of early post-embryonic forms than was hitherto possible. Specifically, we describe five transitional forms during a period in which just two (Peripatoid and Foetus) have traditionally been recognized
Keywords: MOULT DEVELOPMENT ARTHROPOD POST-EMBRYONIC STAGE MORPHOLOGICAL CHANGE MYRIAPOD CENTIPEDE EVO-DEVO
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Leroy, C., Corbara, B., Dejean, A., & Céréghino, R. (2009). Potential sources of nitrogen in an ant-garden tank-bromeliad. Plant. Signal. Behav., 4(9), 868–870.
Abstract: Epiphytic plants in general and bromeliads in particular live in a water and nutrient-stressed environment often limited in nitrogen. Thus, these plants have developed different ways to survive in such an environment. We focused on Aechmea mertensii (Bromeliaceae), which is both a tank-bromeliad and an ant-garden (AG) epiphyte initiated by either the ants Camponotus femoratus or Pachycondyla goeldii. By combining a study of plant morphology and physiology associated with aquatic insect biology, we demonstrate that the ant species influences the leaf structure of the bromeliad, the structure of the aquatic community in its tank, and nutrient assimilation by the leaves. Based on nitrogen and nitrogen stable isotope measurements of the A. mertensii leaves, the leaf litter inside of the tank and the root-embedded carton nest, we discuss the potential sources of available nitrogen for the plant based on the ant partner. We demonstrate the existence of a complex ant-plant interaction that subsequently affects the biodiversity of a broader range of organisms that are themselves likely to influence nutrient assimilation by the A. mertensii leaves in a kind of plant-invertebrate-plant feedback loop.
Keywords: Aechmea mertensii Camponotus femoratus nitrogen nitrogen stable isotope Pachycondyla goeldii plant-insect interactions phytotelmata
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Baraloto, C., Ferreira, E., Rockwell, C., & Walthier, F. (2007). Limitations and Applications of Parataxonomy for Community Forest Management in Southwestern Amazonia. Ethnobotany Research & Applications, 5, 77–84.
Abstract: We examined the limitations of parataxonomic inventories for developing management plans for woody plant resources in tropical rain forests of southwestern Amazonia. Using compilations of herbarium labels, forest personnel interviews and published species descriptions, we assessed the accuracy of common names as parataxonomic units (PUs). We identified 384 common names for 310 harvested woody plant species in the Brazilian state of Acre, of which only 50% were unique to a single taxonomic species. About 10% of common names referred to more than one species, more than half of which included multiple genera. For the 106 species from the Acre sample common to the MAP region including Madre de Dios, Peru and Pando, Bolivia, we identified 198 common names. Splitting was much more frequent in this sample, with more than 80% of species having more than one common name. When the Acre sample was expanded to 131 species from the Brazilian Amazon region, including the states of Amazonas and Para, we identified 740 common names, with nearly 90% of species being represented by more than one common name. Errors and inaccuracy of parataxonomy may contribute to market instability if product orders can not be homogenized within regional markets, and to unsustainable harvests if species are mistakenly lumped into single parataxonomic units. We discuss several programs currently being implemented by our collaborative team in the region to address this issue, including field guides based on digital photography, field courses, and workshops featuring discussions between regional inventory personnel and botanists.
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Vedel, V., Apostolou, Z., Arthur, W., Akam, M., & Brena, C. (2010). An early temperature-sensitive period for the plasticity of segment number in the centipede Strigamia maritima. Evol Dev, 12(4), 347–352.
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Petillon, J., Lambeets, K., Montaigne, W., Maelfait, J. P., & Bonte, D. (2010). Habitat structure modified by an invasive grass enhances inundation withstanding in a salt-marsh wolf spider. Biological Invasions, 12(9), 3219–3226.
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Petillon, J., Montaigne, W., & Renault, D. (2009). Hypoxic coma as a strategy to survive inundation in a salt-marsh inhabiting spider. Biol. Lett., 5(4), 442–445.
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