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ter Steege, H.; Pitman, N.C.A.; Sabatier, D.; Baraloto, C.; Salomão, R.P.; Guevara, J.E.; Phillips, O.L.; Castilho, C.V.; Magnusson, W.E.; Molino, J.-F.; Monteagudo, A.; Núñez Vargas, P.; Montero, J.C.; Feldpausch, T.R.; Coronado, E.N.H.; Killeen, T.J.; Mostacedo, B.; Vasquez, R.; Assis, R.L.; Terborgh, J.; Wittmann, F.; Andrade, A.; Laurance, W.F.; Laurance, S.G.W.; Marimon, B.S.; Marimon, B.-H.; Guimarães Vieira, I.C.; Amaral, I.L.; Brienen, R.; Castellanos, H.; Cárdenas López, D.; Duivenvoorden, J.F.; Mogollón, H.F.; Matos, F.D. de A.; Dávila, N.; García-Villacorta, R.; Stevenson Diaz, P.R.; Costa, F.; Emilio, T.; Levis, C.; Schietti, J.; Souza, P.; Alonso, A.; Dallmeier, F.; Montoya, A.J.D.; Fernandez Piedade, M.T.; Araujo-Murakami, A.; Arroyo, L.; Gribel, R.; Fine, P.V.A.; Peres, C.A.; Toledo, M.; Aymard C., G.A.; Baker, T.R.; Cerón, C.; Engel, J.; Henkel, T.W.; Maas, P.; Petronelli, P.; Stropp, J.; Zartman, C.E.; Daly, D.; Neill, D.; Silveira, M.; Paredes, M.R.; Chave, J.; Lima Filho, D. de A.; Jørgensen, P.M.; Fuentes, A.; Schöngart, J.; Cornejo Valverde, F.; Di Fiore, A.; Jimenez, E.M.; Peñuela Mora, M.C.; Phillips, J.F.; Rivas, G.; van Andel, T.R.; von Hildebrand, P.; Hoffman, B.; Zent, E.L.; Malhi, Y.; Prieto, A.; Rudas, A.; Ruschell, A.R.; Silva, N.; Vos, V.; Zent, S.; Oliveira, A.A.; Schutz, A.C.; Gonzales, T.; Trindade Nascimento, M.; Ramirez-Angulo, H.; Sierra, R.; Tirado, M.; Umaña Medina, M.N.; van der Heijden, G.; Vela, C.I.A.; Vilanova Torre, E.; Vriesendorp, C.; Wang, O.; Young, K.R.; Baider, C.; Balslev, H.; Ferreira, C.; Mesones, I.; Torres-Lezama, A.; Urrego Giraldo, L.E.; Zagt, R.; Alexiades, M.N.; Hernandez, L.; Huamantupa-Chuquimaco, I.; Milliken, W.; Palacios Cuenca, W.; Pauletto, D.; Valderrama Sandoval, E.; Valenzuela Gamarra, L.; Dexter, K.G.; Feeley, K.; Lopez-Gonzalez, G.; Silman, M.R. |
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Hyperdominance in the Amazonian Tree Flora |
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Journal Article |
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2013 |
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Science |
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Science |
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342 |
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6156 |
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1243092 |
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The vast extent of the Amazon Basin has historically restricted the study of its tree communities to the local and regional scales. Here, we provide empirical data on the commonness, rarity, and richness of lowland tree species across the entire Amazon Basin and Guiana Shield (Amazonia), collected in 1170 tree plots in all major forest types. Extrapolations suggest that Amazonia harbors roughly 16,000 tree species, of which just 227 (1.4%) account for half of all trees. Most of these are habitat specialists and only dominant in one or two regions of the basin. We discuss some implications of the finding that a small group of species—less diverse than the North American tree flora—accounts for half of the world’s most diverse tree community. |
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EcoFoG @ webmaster @ |
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Dezerald, O.; Talaga, S.; Leroy, C.; Carrias, J.-F.; Corbara, B.; Dejean, A.; Céréghino, R. |
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Environmental determinants of macroinvertebrate diversity in small water bodies: Insights from tank-bromeliads |
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Journal Article |
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2014 |
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Hydrobiologia |
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Hydrobiologia |
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723 |
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1 |
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77-86 |
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Freshwater biodiversity; Linear mixed effect modelling; Microcosms; Phytotelmata; Ponds |
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The interlocking leaves of tank-forming bromeliads (Bromeliaceae) collect rainwater and detritus, thus creating a freshwater habitat for specialized organisms. Their abundance and the possibility of quantifying communities with accuracy give us unparalleled insight into how changes in local to regional environments influence community diversity in small water bodies. We sampled 365 bromeliads (365 invertebrate communities) along a southeastern to northwestern range in French Guiana. Geographic locality determined the species pool for bromeliad invertebrates, and local environments determined the abundance patterns through the selection of traits that are best adapted to the bromeliad habitats. Patterns in community structure mostly emerged from patterns of predator species occurrence and abundance across local-regional environments, while the set of detritivores remained constant. Water volume had a strong positive correlation with invertebrate diversity, making it a biologically relevant measure of the pools' carrying capacity. The significant effects of incoming detritus and incident light show that changes in local environments (e.g., the conversion of forest to cropping systems) strongly influence freshwater communities. Because changes in local environments do not affect detritivores and predators equally, one may expect functional shifts as sets of invertebrates with particular traits are replaced or complemented by other sets with different traits. © 2013 Springer Science+Business Media Dordrecht. |
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CNRS, EcoLab (UMR-CNRS 5245), 118 Route de Narbonne, 31062 Toulouse, France |
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EcoFoG @ webmaster @ |
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517 |
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Lang, G.; Marcon, E. |
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Testing randomness of spatial point patterns with the Ripley statistic |
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2013 |
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ESAIM: Probability and Statistics |
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ESAIM PS |
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17 |
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767-788 |
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Central limit theorem, goodness-of-fit test, Höffding decomposition, null, point pattern, Poisson process, null |
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Aggregation patterns are often visually detected in sets of location data. These clusters may be the result of interesting dynamics or the effect of pure randomness. We build an asymptotically Gaussian test for the hypothesis of randomness corresponding to a homogeneous Poisson point process. We first compute the exact first and second moment of the Ripley K-statistic under the homogeneous Poisson point process model. Then we prove the asymptotic normality of a vector of such statistics for different scales and compute its covariance matrix. From these results, we derive a test statistic that is chi-square distributed. By a Monte-Carlo study, we check that the test is numerically tractable even for large data sets and also correct when only a hundred of points are observed |
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518 |
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Groc, S.; Delabie, J.H.C.; Fernández, F.; Leponce, M.; Orivel, J.; Silvestre, R.; Vasconcelos, H.L.; Dejean, A. |
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Leaf-litter ant communities in a pristine Guianese rainforest: stable functional structure versus high species turnover |
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2013 |
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Myrmecological News |
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Myrmecol. News |
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19 |
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43-51 |
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523 |
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Leroy, C.; Gril, E.; Si Ouali, L.; Coste, S.; Gérard, B.; Maillard, P.; Mercier, H.; Stahl, C. |
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Water and nutrient uptake capacity of leaf-absorbing trichomes vs. roots in epiphytic tank bromeliads |
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Journal Article |
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2019 |
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Environmental and Experimental Botany |
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Environ. Exp. Bot. |
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163 |
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112-123 |
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15 N labelling; Carbon metabolism; Nutrient uptake; Plant performance; Tank bromeliad; Water status; Aechmea |
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The water and nutrient uptake mechanisms used by vascular epiphytes have been the subject of a few studies. While leaf absorbing trichomes (LATs) are the main organ involved in resource uptake by bromeliads, little attention has been paid to the absorbing role of epiphytic bromeliad roots. This study investigates the water and nutrient uptake capacity of LATs vs. roots in two epiphytic tank bromeliads Aechmea aquilega and Lutheria splendens. The tank and/or the roots of bromeliads were watered, or not watered at all, in different treatments. We show that LATs and roots have different functions in resource uptake in the two species, which we mainly attributed to dissimilarities in carbon acquisition and growth traits (e.g., photosynthesis, relative growth rate, non-structural carbohydrates, malate), to water relation traits (e.g., water and osmotic potentials, relative water content, hydrenchyma thickness) and nutrient uptake (e.g., 15 N-labelling). While the roots of A. aquilega did contribute to water and nutrient uptake, the roots of L. splendens were less important than the role played by the LATs in resource uptake. We also provide evidenced for a synergistic effect of combined watering of tank and root in the Bromelioideae species. These results call for a more complex interpretation of LATs vs. roots in resource uptake in bromeliads. © 2019 Elsevier B.V. |
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INRA, UMR EcoFoG, CNRS, CIRAD, AgroParisTech, Université des Antilles, Université de Guyane, Kourou, 97310, France |
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Elsevier B.V. |
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00988472 (Issn) |
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EcoFoG @ webmaster @ |
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871 |
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Steidinger, B.S.; Crowther, T.W.; Liang, J.; Van Nuland, M.E.; Werner, G.D.A.; Reich, P.B.; Nabuurs, G.; de-Miguel, S.; Zhou, M.; Picard, N.; Herault, B.; Zhao, X.; Zhang, C.; Routh, D.; Peay, K.G.; Abegg, M.; Adou Yao, C.Y.; Alberti, G.; Almeyda Zambrano, A.; Alvarez-Davila, E.; Alvarez-Loayza, P.; Alves, L.F.; Ammer, C.; Antón-Fernández, C.; Araujo-Murakami, A.; Arroyo, L.; Avitabile, V.; Aymard, G.; Baker, T.; Bałazy, R.; Banki, O.; Barroso, J.; Bastian, M.; Bastin, J.-F.; Birigazzi, L.; Birnbaum, P.; Bitariho, R.; Boeckx, P.; Bongers, F.; Bouriaud, O.; Brancalion, P.H.S.; Brandl, S.; Brearley, F.Q.; Brienen, R.; Broadbent, E.; Bruelheide, H.; Bussotti, F.; Cazzolla Gatti, R.; Cesar, R.; Cesljar, G.; Chazdon, R.; Chen, H.Y.H.; Chisholm, C.; Cienciala, E.; Clark, C.J.; Clark, D.; Colletta, G.; Condit, R.; Coomes, D.; Cornejo Valverde, F.; Corral-Rivas, J.J.; Crim, P.; Cumming, J.; Dayanandan, S.; de Gasper, A.L.; Decuyper, M.; Derroire, G.; DeVries, B.; Djordjevic, I.; Iêda, A.; Dourdain, A.; Obiang, N.L.E.; Enquist, B.; Eyre, T.; Fandohan, A.B.; Fayle, T.M.; Feldpausch, T.R.; Finér, L.; Fischer, M.; Fletcher, C.; Fridman, J.; Frizzera, L.; Gamarra, J.G.P.; Gianelle, D.; Glick, H.B.; Harris, D.; Hector, A.; Hemp, A.; Hengeveld, G.; Herbohn, J.; Herold, M.; Hillers, A.; Honorio Coronado, E.N.; Huber, M.; Hui, C.; Cho, H.; Ibanez, T.; Jung, I.; Imai, N.; Jagodzinski, A.M.; Jaroszewicz, B.; Johannsen, V.; Joly, C.A.; Jucker, T.; Karminov, V.; Kartawinata, K.; Kearsley, E.; Kenfack, D.; Kennard, D.; Kepfer-Rojas, S.; Keppel, G.; Khan, M.L.; Killeen, T.; Kim, H.S.; Kitayama, K.; Köhl, M.; Korjus, H.; Kraxner, F.; Laarmann, D.; Lang, M.; Lewis, S.; Lu, H.; Lukina, N.; Maitner, B.; Malhi, Y.; Marcon, E.; Marimon, B.S.; Marimon-Junior, B.H.; Marshall, A.R.; Martin, E.; Martynenko, O.; Meave, J.A.; Melo-Cruz, O.; Mendoza, C.; Merow, C.; Monteagudo Mendoza, A.; Moreno, V.; Mukul, S.A.; Mundhenk, P.; Nava-Miranda, M.G.; Neill, D.; Neldner, V.; Nevenic, R.; Ngugi, M.; Niklaus, P.; Oleksyn, J.; Ontikov, P.; Ortiz-Malavasi, E.; Pan, Y.; Paquette, A.; Parada-Gutierrez, A.; Parfenova, E.; Park, M.; Parren, M.; Parthasarathy, N.; Peri, P.L.; Pfautsch, S.; Phillips, O.; Piedade, M.T.; Piotto, D.; Pitman, N.C.A.; Polo, I.; Poorter, L.; Poulsen, A.D.; Poulsen, J.R.; Pretzsch, H.; Ramirez Arevalo, F.; Restrepo-Correa, Z.; Rodeghiero, M.; Rolim, S.; Roopsind, A.; Rovero, F.; Rutishauser, E.; Saikia, P.; Saner, P.; Schall, P.; Schelhaas, M.-J.; Schepaschenko, D.; Scherer-Lorenzen, M.; Schmid, B.; Schöngart, J.; Searle, E.; Seben, V.; Serra-Diaz, J.M.; Salas-Eljatib, C.; Sheil, D.; Shvidenko, A.; Silva-Espejo, J.; Silveira, M.; Singh, J.; Sist, P.; Slik, F.; Sonké, B.; Souza, A.F.; Stereńczak, K.; Svenning, J.-C.; Svoboda, M.; Targhetta, N.; Tchebakova, N.; Steege, H.; Thomas, R.; Tikhonova, E.; Umunay, P.; Usoltsev, V.; Valladares, F.; van der Plas, F.; Van Do, T.; Vasquez Martinez, R.; Verbeeck, H.; Viana, H.; Vieira, S.; von Gadow, K.; Wang, H.-F.; Watson, J.; Westerlund, B.; Wiser, S.; Wittmann, F.; Wortel, V.; Zagt, R.; Zawila-Niedzwiecki, T.; Zhu, Z.-X.; Zo-Bi, I.C.; GFBI consortium |
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Climatic controls of decomposition drive the global biogeography of forest-tree symbioses |
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Journal Article |
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2019 |
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Nature |
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Nature |
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569 |
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7756 |
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404-408 |
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Fungi |
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The identity of the dominant root-associated microbial symbionts in a forest determines the ability of trees to access limiting nutrients from atmospheric or soil pools 1,2 , sequester carbon 3,4 and withstand the effects of climate change 5,6 . Characterizing the global distribution of these symbioses and identifying the factors that control this distribution are thus integral to understanding the present and future functioning of forest ecosystems. Here we generate a spatially explicit global map of the symbiotic status of forests, using a database of over 1.1 million forest inventory plots that collectively contain over 28,000 tree species. Our analyses indicate that climate variables—in particular, climatically controlled variation in the rate of decomposition—are the primary drivers of the global distribution of major symbioses. We estimate that ectomycorrhizal trees, which represent only 2% of all plant species 7 , constitute approximately 60% of tree stems on Earth. Ectomycorrhizal symbiosis dominates forests in which seasonally cold and dry climates inhibit decomposition, and is the predominant form of symbiosis at high latitudes and elevation. By contrast, arbuscular mycorrhizal trees dominate in aseasonal, warm tropical forests, and occur with ectomycorrhizal trees in temperate biomes in which seasonally warm-and-wet climates enhance decomposition. Continental transitions between forests dominated by ectomycorrhizal or arbuscular mycorrhizal trees occur relatively abruptly along climate-driven decomposition gradients; these transitions are probably caused by positive feedback effects between plants and microorganisms. Symbiotic nitrogen fixers—which are insensitive to climatic controls on decomposition (compared with mycorrhizal fungi)—are most abundant in arid biomes with alkaline soils and high maximum temperatures. The climatically driven global symbiosis gradient that we document provides a spatially explicit quantitative understanding of microbial symbioses at the global scale, and demonstrates the critical role of microbial mutualisms in shaping the distribution of plant species. © 2019, The Author(s), under exclusive licence to Springer Nature Limited. |
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Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, Ås, Norway |
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Nature Publishing Group |
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00280836 (Issn) |
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872 |
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Salhi, L.; Nait-Rabah, O.; Deyrat, C.; Roos, C. |
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Numerical Modeling of Single Helical Pile Behavior under Compressive Loading in Sand |
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Journal Article |
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2013 |
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Electronic Journal of Geotechnical Engineering |
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Electron. J. Geotech. Eng. |
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18 |
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Bundle T |
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4119-4338 |
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helical pile; finite element method; failure mechanisms; sand |
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The present research deals with helical piles behavior in cohesionless soil through finite element modeling. An approach of modeling of the screw-pile geometry has been proposed through the Finite Element Analysis (FEA) computer program Plaxis. The numerical results are compared with measurements from large scale test and the bearing capacity has been estimated using both cylindrical and individual bearing model. Moreover, different failure criterions have been applied to estimate the ultimate capacity. The effect of spacing ratio (S/Dh) on the screw-pile behavior has been further studied. It has found that results from the model fit the field results. Through the study of the load transfer mechanism, the transition from cylindrical shear to individual plate behavior occurs at a value of spacing ratio (1.5 to 2). |
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Laboratoire des matériaux et molécules en milieu amazonien, EcoFoG-Université des Antilles-Guyane, 97351 Cayenne, French Guiana |
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Petit, M.; Céréghino, R.; Carrias, J.-F.; Corbara, B.; Dezerald, O.; Petitclerc, F.; Dejean, A.; Leroy, C. |
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Are ontogenetic shifts in foliar structure and resource acquisition spatially conditioned in tank-bromeliads? |
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2014 |
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Botanical Journal of the Linnean Society |
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Bot J Linn Soc |
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175 |
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2 |
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299-312 |
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Aechmea mertensii; Camponotus femoratus; French Guiana; leaf traits; mutualistic ants; natural stable isotopes; ontogeny; Pachycondyla goeldii; phenotypic plasticity; plant morphology |
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The phenotypic plasticity of plants has been explored as a function of either ontogeny (apparent plasticity) or environment (adaptive plasticity), although few studies have analyzed these factors together. In the present study, we take advantage of the dispersal of Aechmea mertensii bromeliads by Camponotus femoratus or Pachycondyla goeldii ants in shaded and sunny environments, respectively, to quantify ontogenetic changes in morphological, foliar, and functional traits, and to analyze ontogenetic and ant species effects on 14 traits. Most of the morphological (plant height, number of leaves), foliar (leaf thickness, leaf mass area, total water content, trichome density), and functional (leaf δ13C) traits differed as a function of ontogeny. Conversely, only leaf δ15N showed an adaptive phenotypic plasticity. On the other hand, plant width, tank width, longest leaf length, stomatal density, and leaf C concentration showed an adaptation to local environment with ontogeny. The exception was leaf N concentration, which showed no trend at all. Aechmea mertensii did not show an abrupt morphological modification such as in heteroblastic bromeliads, although it was characterized by strong, size-related functional modifications for CO2 acquisition. The adaptive phenotypic variation found between the two ant species indicates the spatially conditioned plasticity of A. mertensii in the context of insect-assisted dispersal. However, ant-mediated effects on phenotypic plasticity in A. mertensii are not obvious because ant species and light environment are confounding variables. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 175, 299–312. |
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EcoFoG @ webmaster @ |
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564 |
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Biwolé, A.B.; Dainou, K.; Fayolle, A.; Hardy, O.J.; Brostaux, Y.; Coste, S.; Delion, S.; Betti, J.L.; Doucet, J.-L. |
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Title |
Light Response of Seedlings of a Central African Timber Tree Species, Lophira alata (Ochnaceae), and the Definition of Light Requirements |
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Journal Article |
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Year |
2015 |
Publication |
Biotropica |
Abbreviated Journal |
Biotropica |
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47 |
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6 |
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681-688 |
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Keywords |
biomass allocation; Central Africa; light requirement: Lophira alata; population; relative growth rate; seedling growth; timber species; Afrique centrale; allocation de biomasse; besoins en lumière; croissance des semis; bois d'œuvre; Lophira alata; population; taux de croissance relatif |
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Abstract |
Light is of primary importance in structuring tropical tree communities. Light exposure at seedling and adult stages has been used to characterize the ecological profile of tropical trees, with many implications in forest management and restoration ecology. Most shade-tolerance classification systems have been proposed based on empirical observations in a specific area and thus result in contradictions among categories assigned to a given species. In this study, we aimed to quantify the light requirements for seedling growth of a Central African timber tree, Lophira alata (Ochnaceae), taking into account effects of population origin. In two controlled experiments: a light response experiment and a comparative population experiment, conducted in southwestern Cameroon, using seeds collected from four populations (three from Cameroon and one from Gabon), we examined the quantitative responses to irradiance of seedlings. After 2 years, mortality was very low (<3%), even in extremely low irradiance. Growth and biomass allocation patterns varied in response to light, with intermediate irradiance (24–43%) providing optimal conditions. Light response differed between populations. The Boumba population in the northeastern edge of the species' distribution exhibited the highest light requirements, suggesting a local adaptation. As a result of positive growth at low irradiance and maximum growth at intermediate irradiance, we concluded that L. alata exhibits characteristics of both non-pioneer and pioneer species. Implications of our results to propose an objective way to assign the light requirement for tropical tree species are discussed. |
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1744-7429 |
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EcoFoG @ webmaster @ |
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648 |
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Houel, E.; Fleury, M.; Odonne, G.; Nardella, F.; Bourdy, G.; Vonthron-Sénécheau, C.; Villa, P.; Obrecht, A.; Eparvier, V.; Deharo, E.; Stien, D. |
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Antiplasmodial and anti-inflammatory effects of an antimalarial remedy from the Wayana Amerindians, French Guiana: Takamalaimë (Psidium acutangulum Mart. ex DC., Myrtaceae) |
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Journal Article |
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2015 |
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Journal of Ethnopharmacology |
Abbreviated Journal |
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166 |
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279-285 |
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Psidium acutangulum; Plasmodium; Cytokines; Antimalarial; French Guiana; Traditional medicine |
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Ethnopharmacological relevance:
Field investigations highlighted the use of Psidium acutangulum Mart. ex DC (syn. P. persoonii McVaugh), a small tree used by the Wayana Amerindians in Twenke–Taluhwen and Antecume–Pata, French Guiana, for the treatment of malaria, and administered either orally in the form of a decoction or applied externally over the whole body. This use appears limited to the Wayana cultural group in French Guiana and has never been reported anywhere else. Our goal was to evaluate the antimalarial and anti-inflammatory activities of a P. acutangulum decoction to explain the good reputation of this remedy.
Materials and methods:
Interviews with the Wayana inhabitants of Twenke–Taluhwen and Antecume–Pata were conducted within the TRAMAZ project according to the TRAMIL methodology, which is based on a quantitative and qualitative analysis of medicinal plant uses. A decoction of dried aerial parts of P. acutangulum was prepared in consistency with the Wayana recipe. In vitro antiplasmodial assays were performed on chloroquine-resistant FcB1 ([3H]-hypoxanthine bioassay) and 7G8 (pLDH bioassay) P. falciparum strains and on chloroquine sensitive NF54 ([3H]-hypoxanthine bioassay) P. falciparum strain. In vitro anti-inflammatory activity (IL-1β, IL-6, IL-8, TNFα) was evaluated on LPS-stimulated human PBMC and NO secretion inhibition was measured on LPS stimulated RAW murine macrophages. Cytotoxicity of the decoction was measured on L6 mammalian cells, PBMCs, and RAW cells. A preliminary evaluation of the in vivo antimalarial activity of the decoction, administered orally twice daily, was assessed by the classical four-day suppressive test against P. berghei NK65 in mice.
Results:
The decoction displayed a good antiplasmodial activity in vitro against the three tested strains, regardless to the bioassay used, with IC50 values of 3.3 µg/mL and 10.3 µg/mL against P. falciparum FcB1 and NF54, respectively and 19.0 µg/mL against P. falciparum 7G8. It also exhibited significant anti-inflammatory activity in vitro in a dose dependent manner. At a concentration of 50 µg/mL, the decoction inhibited the secretion of the following pro-inflammatory cytokines: TNFα (−18%), IL-1β (−58%), IL-6 (−32%), IL-8 (−21%). It also exhibited a mild NO secretion inhibition (−13%) at the same concentration. The decoction was non-cytotoxic against L6 cells (IC50>100 µg/mL), RAW cells and PBMC. In vivo, 150 µL of the decoction given orally twice a day (equivalent to 350 mg/kg/day of dried extract) inhibited 39.7% average parasite growth, with more than 50% of inhibition in three mice over five. The absence of response for the two remaining mice, however, induced a strong standard deviation.
Conclusions:
This study highlighted the in vitro antiplasmodial activity of the decoction of P. acutangulum aerial parts, used by Wayana Amerindians from the Upper-Maroni in French Guiana in case of malaria. Its antioxidant and anti-inflammatory potential, which may help to explain its use against this disease, was demonstrated using models of artificially stimulated cells. |
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0378-8741 |
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EcoFoG @ webmaster @ |
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649 |
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