Sarmiento, C., Patino, S., Paine, C. E. T., Beauchene, J., Thibaut, A., & Baraloto, C. (2011). Within-Individual Variation of Trunk and Branch Xylem Density in Tropical Trees. Am. J. Bot., 98(1), 140–149.
Abstract: Premise of the study : Wood density correlates with mechanical and physiological strategies of trees and is important for estimating global carbon stocks. Nonetheless, the relationship between branch and trunk xylem density has been poorly explored in neotropical trees. Here, we examine this relationship in trees from French Guiana and its variation among different families and sites, to improve the understanding of wood density in neotropical forests. Methods : Trunk and branch xylem densities were measured for 1909 trees in seven sites across French Guiana. A major-axis fit was performed to explore their general allometric relationship and its variation among different families and sites. Key results : Trunk xylem and branch xylem densities were significantly positively correlated, and their relationship explained 47% of the total variance. Trunk xylem was on average 9% denser than branch xylem. Family-level differences and interactions between family and site accounted for more than 40% of the total variance, whereas differences among sites explained little variation. Conclusions : Variation in xylem density within individual trees can be substantial, and the relationship between branch xylem and trunk xylem densities varies considerably among families and sites. As such, whole-tree biomass estimates based on non-destructive branch sampling should correct for both taxonomic and environmental factors. Furthermore, detailed estimates of the vertical distribution of wood density within individual trees are needed to determine the extent to which relying solely upon measures of trunk wood density may cause carbon stocks in tropical forests to be overestimated.
Keywords: branch xylem density; French Guiana; functional trait; tropical trees; trunk xylem density; wood economics
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Leroy, C., Cereghino, R., Camas, J. F., Pelozuelo, L., Dejean, A., & Corbara, B. (2010). Several aspects of the life of vascular epiphytes. Biofutur, 315, 38–41.
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Orivel, J., Corbara, B., & Dejean, A. (2010). Constraints and adaptation in the arboreal life of ants. Biofutur, 315, 34–37.
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Paine, C. E. T., Stahl, C., Courtois, E. A., Patino, S., Sarmiento, C., & Baraloto, C. (2010). Functional explanations for variation in bark thickness in tropical rain forest trees. Funct. Ecol., 24(6), 1202–1210.
Abstract: P>1. The complex structure of tree bark reflects its many functions, which include structural support as well as defence against fire, pests and pathogens. Thick bark, however, might limit respiration by the living tissues of the trunk. Nevertheless, little research has addressed community-level variation in bark thickness, and to the best of our knowledge, no one has tested multiple hypotheses to explain variation in bark thickness. 2. We conducted an extensive survey of bark thickness within and among species of trees in the tropical rain forests of French Guiana. Trunk bark thickness increased by 1 center dot 2 mm per 10 cm increase in stem diameter, and varied widely at all taxonomic levels. Mean trunk bark thickness was 4 center dot 5 mm (range: 0 center dot 5-29 mm), which was less that found in two Amazonian rain forests in previous studies. This survey of bark thickness should be of use for forest management since tree survival through fire is strongly predicted by bark thickness. 3. We combined the survey data with multiple datasets to test several functional hypotheses proposed to explain variation in bark thickness. We found bark to provide an average of 10% of the flexural rigidity of tree stems, which was substantially less than that found in the only other study of bark stiffness. Bark thickness was uncorrelated with species' association with fire-prone habitats, suggesting that the influence of fire on bark thickness does not extend into moist Forests. There was also little evidence that bark thickness is affected by its function as a defence against herbivory. Nor was there evidence that thick bark limits trunk respiration. 4. A re-analysis of previously collected anatomical data indicated that variation in rhytidome (non-conducting outer bark) thickness explains much of the variation in overall bark thickness. As rhytidome is primarily involved in protecting the living tissues of the trunk, we suggest that bark thickness is driven mostly by its defensive function. 5. Functional explanations for the variation in bark thickness were not clear-cut. Nevertheless, this study provides a foundation for further investigation of the functional bases of bark in tropical trees.
Keywords: bark thickness; fire ecology; flexural rigidity; herbivore defence; periderm; rhytidome; trunk respiration
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Cabanillas, B. J., Le Lamer, A. C., Castillo, D., Arevalo, J., Rojas, R., Odonne, G., et al. (2010). Caffeic Acid Esters and Lignans from Piper sanguineispicum. J. Nat. Prod., 73(11), 1884–1890.
Abstract: Three new caffeic acid esters (1-3), four new lignans (4-7), and the known compounds (7'S)-parabenzlactone (8), dihydrocubebin (9), and justiflorinol (10) have been isolated from leaves of Piper sanguineispicum. Their structures were determined by spectroscopic methods, including 1D and 2D NMR, HRCIMS, CD experiments, and chemical methods. Compounds 1-10 were assessed for their antileishmanial potential against axenic amastigote forms of Leishmania amazonensis. Caffeic acid esters 1 and 3 exhibited the best antileishmanial activity (IC50 2.0 and 1.8 μM, respectively) with moderate cytotoxicity on murine macrophages.
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Male, P. J. G., Loiseau, A., Estoup, A., Quilichini, A., & Orivel, J. (2010). Characterization of polymorphic microsatellite loci in the neotropical plant-ant Allomerus decemarticulatus (Formicidae: Myrmicinae) and multiplexing with other microsatellites from the ant subfamily Myrmicinae. Eur. J. Entomol., 107(4), 673–675.
Abstract: Five polymorphic microsatellite loci of the arboreal ant Allomerus decemarticulatus (Myrmicinae) were isolated and characterized. The amplification and polymorphism of seven additional microsatellite loci, previously developed for the ant species A. octoarticulatus and Wasmannia auropunctata, were also tested and the amplification conditions necessary for genotyping the complete set of 12 multiplexed markers in A. decemarticulatus determined. The number of alleles per locus ranged from three to 15 and observed heterozygosity varied front 0.09 to 0.95. Cross-species amplification of these loci was also successfully achieved in additional species of the same ant subfamily, Myrmicinae. This set of microsatellite markers will be used in studies on the mating system and population genetic structure of Myrmicinae in general and A. decemarticulatus in particular.
Keywords: Hymenoptera; Formicidae; Myrmicinae; Allomerus; ant-plant mutualism; microsatellites; plant-ant
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Lebrini, M., Robert, F., & Roos, C. (2010). Inhibition Effect of Alkaloids Extract from Annona Squamosa Plant on the Corrosion of C38 Steel in Normal Hydrochloric Acid Medium. Int. J. Electrochem. Sci., 5(11), 1698–1712.
Abstract: In this work, an alkaloids extract from Annona squamosa plant have been studied as possible corrosion inhibitor for C38 steel in molar hydrochloric acid (1 M HCl). Potentiodynamic polarization and AC impedance methods have been used. The corrosion inhibition efficiency increases on increasing plant extract concentration. Polarisation studies showed that Annona squamosa extract was mixed-type inhibitor in 1 M HCl. The inhibition efficiency of Annona squamosa extract was temperature-dependent and its addition led to an increase of the activation corrosion energy revealing a physical adsorption between the extract and the metal surface. The adsorption of the Annona squamosa extract followed Langmuir's adsorption isotherm. The inhibitive effect of Annona squamosa is ascribed to the presence of organic compounds in the extract. The examined extract is considered as non-cytotoxic substance.
Keywords: Plant extract; corrosion inhibitors; C38 steel; acidic media; adsorption
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Wagner, F., Rutishauser, E., Blanc, L., & Herault, B. (2010). Effects of Plot Size and Census Interval on Descriptors of Forest Structure and Dynamics. Biotropica, 42(6), 664–671.
Abstract: This study was designed to explicitly formulate the effect of census interval and plot size on the variability of descriptors of tropical forest structure (stand density, basal area, aboveground biomass [AGB]) and dynamic (tree growth, mortality and recruitment rates, biomass fluxes). A unique dataset from a broad plot network (37.5 ha) surveyed every 2 yr over a 16-yr period was used to develop and parameterize a new statistical model predicting the coefficients of variation for each forest descriptor. More than 90 percent of the inherent variability of these coefficients was predicted using a simple model including plot size and census interval in a Bayesian modeling framework. All descriptors of forest structure varied by <10 percent for plot sizes 42 ha. Among the descriptors of forest dynamics, AGB loss was the most variable. The number of 6.25 ha plots required to estimate its mean, over a 16-yr period, within a 20 percent error of the mean remains above four. This contrasts with a relative constant flux of biomass entering the plot through tree growth and tree recruitment. Tree growth was remarkably well estimated with <15 percent variability for a 2-yr census in a plot of 2 ha. This study provides an easy method to assess dataset limitations in efforts to estimate descriptors of forest structure and dynamic, which is of primary importance to decipher any clear consequences of global change in tropical forests.
Keywords: Amazonia; biomass fluxes; coefficient of variation; forest permanent plots; turnover rates; WinBUGS
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Scotti, I. (2010). Adaptive potential in forest tree populations: what is it, and how can we measure it? Ann. For. Sci., 67(8), 801.
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Marti, G., Eparvier, V., Litaudon, M., Grellier, P., & Gueritte, F. (2010). A New Xanthone from the Bark Extract of Rheedia acuminata and Antiplasmodial Activity of Its Major Compounds. Molecules, 15(10), 7106–7114.
Abstract: Bioassay-guided fractionation of the ethyl acetate bark extract of Rheedia acuminata led to the isolation of the new compound 1,5,6-trihydroxy-3-methoxy-7-geranyl-xanthone (1), together with four known compounds 2-5. These compounds were tested in vitro for their antiplasmodial activity on a chloroquine-resistant strain of Plasmodium falciparum (FcB1) and for their cytotoxicity against the human diploid embryonic lung cell line MRC-5.
Keywords: Rheedia acuminata, Clusiaceae; xanthones; antiplasmodial activity; cytotoxicity
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