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| Author |
Marcon, E.; Traissac, S.; Lang, G. |
| Title |
A Statistical Test for Ripley’s Function Rejection of Poisson Null Hypothesis |
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Journal Article |
| Year |
2013 |
Publication |
ISRN Ecology |
Abbreviated Journal |
ISRN Ecology |
| Volume |
2013 |
Issue |
Article ID 753475 |
Pages |
9 |
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| Abstract |
Ripley’s K function is the classical tool to characterize the spatial structure of point patterns. It is widely used in vegetation studies. Testing its values against a null hypothesis usually relies on Monte-Carlo simulations since little is known about its distribution.
We introduce a statistical test against complete spatial randomness (CSR). The test returns the p-value to reject the null hypothesis of independence between point locations. It is more rigorous and faster than classical Monte-Carlo simulations. We show how to apply it to a tropical forest plot. The necessary R code is provided. |
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EcoFoG @ webmaster @ 852 |
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479 |
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Vedel, V.; Lalague, H. |
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Standardized sampling protocol for spider community assessment in the Neotropical rainforest |
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Journal Article |
| Year |
2013 |
Publication |
Journal of Entomology and Zoology Studies |
Abbreviated Journal |
J. Entomol. Zool. Stud. |
| Volume |
2 |
Issue |
1 |
Pages |
18-34 |
| Keywords |
Araneae; Biodiversity; French Guiana; Guianese Shield; Impact Assessment |
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We described, here, a standardized protocol to collect the maximum number of spiders per unit of effort from the different strata of a tropical forestry habitat. This would allow quantifying the richness of a site and would allow spatial and temporal comparisons between sites. This protocol was tested and applied in a pilot study at four sites representing three different forestry habitats of the natural reserve of La Trinité (French Guiana). Results showed every feeding guild was well represented and most of the 30 families found are represented by several individuals. Indices of species richness, number of singletons, species richness estimators from the accumulation curves and diversity and similarity indices were also calculated and all indicated that La Trinité is a rich and diverse site for spiders. The standardized protocol showed here its efficiency and its wide cover of micro-habitats and is, therefore, recommended for any impact assessment or diversity of spider study in tropical forestry environment. |
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EcoFoG @ webmaster @ |
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487 |
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Öpik, M.; Zobel, M.; Cantero, J.J.; Davison, J.; Facelli, J.M.; Hiiesalu, I.; Jairus, T.; Kalwij, J.M.; Koorem, K.; Leal, M.E.; Liira, J.; Metsis, M.; Neshataeva, V.; Paal, J.; Phosri, C.; Põlme, S.; Reier, Ü.; Saks, Ü.; Schimann, H.; Thiéry, O.; Vasar, M.; Moora, M. |
| Title |
Global sampling of plant roots expands the described molecular diversity of arbuscular mycorrhizal fungi |
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Journal Article |
| Year |
2013 |
Publication |
Mycorrhiza |
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23 |
Issue |
5 |
Pages |
411-430 |
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454-sequencing; Biogeography; Database; Diversity; Fungal macroecology; Glomeromycota |
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We aimed to enhance understanding of the molecular diversity of arbuscular mycorrhizal fungi (AMF) by building a new global dataset targeting previously unstudied geographical areas. In total, we sampled 96 plant species from 25 sites that encompassed all continents except Antarctica. AMF in plant roots were detected by sequencing the nuclear SSU rRNA gene fragment using either cloning followed by Sanger sequencing or 454-sequencing. A total of 204 AMF phylogroups (virtual taxa, VT) were recorded, increasing the described number of Glomeromycota VT from 308 to 341 globally. Novel VT were detected from 21 sites; three novel but nevertheless widespread VT (Glomus spp. MO-G52, MO-G53, MO-G57) were recorded from six continents. The largest increases in regional VT number were recorded in previously little-studied Oceania and in the boreal and polar climatic zones – this study providing the first molecular data from the latter. Ordination revealed differences in AM fungal communities between different continents and climatic zones, suggesting that both biogeographic history and environmental conditions underlie the global variation of those communities. Our results show that a considerable proportion of Glomeromycota diversity has been recorded in many regions, though further large increases in richness can be expected in remaining unstudied areas. © 2013 Springer-Verlag Berlin Heidelberg. |
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INRA-Joint Research Unit Ecology of Guiana Forests (Ecofog), campus agronomique, BP 709, 97387 Kourou cedex, French Guiana |
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Export Date: 25 June 2013; Source: Scopus |
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no |
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EcoFoG @ webmaster @ |
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493 |
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Roux, O.; Rossi, V.; Céréghino, R.; Compin, A.; Martin, J.-M.; Dejean, A. |
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How to coexist with fire ants: The roles of behaviour and cuticular compounds |
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Journal Article |
| Year |
2013 |
Publication |
Behavioural Processes |
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98 |
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51-57 |
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Aggressiveness; Cuticular hydrocarbons; Dear enemy phenomenon; Nasty neighbour effect; Species coexistence; Supercoloniality |
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Because territoriality is energetically costly, territorial animals frequently respond less aggressively to neighbours than to strangers, a reaction known as the “dear enemy phenomenon” (DEP). The contrary, the “nasty neighbour effect” (NNE), occurs mainly for group-living species defending resource-based territories. We studied the relationships between supercolonies of the pest fire ant Solenopsis saevissima and eight ant species able to live in the vicinity of its nests plus Eciton burchellii, an army ant predator of other ants. The workers from all of the eight ant species behaved submissively when confronted with S. saevissima (dominant) individuals, whereas the contrary was never true. Yet, S. saevissima were submissive towards E. burchellii workers. Both DEP and NNE were observed for the eight ant species, with submissive behaviours less frequent in the case of DEP. To distinguish what is due to chemical cues from what can be attributed to behaviour, we extracted cuticular compounds from all of the nine ant species compared and transferred them onto a number of S. saevissima workers that were then confronted with untreated conspecifics. The cuticular compounds from three species, particularly E. burchellii, triggered greater aggressiveness by S. saevissima workers, while those from the other species did not. © 2013 Elsevier B.V. |
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Université de Toulouse, UPS, Ecolab, 31062 Toulouse, France |
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Export Date: 1 July 2013; Source: Scopus |
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no |
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EcoFoG @ webmaster @ |
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494 |
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Lebrini, M.; Robert, F.; Roos, C. |
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Adsorption properties and inhibition of C38 steel corrosion in hydrochloric solution by some indole derivates: Temperature effect, activation energies, and thermodynamics of adsorption |
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Journal Article |
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2013 |
Publication |
International Journal of Corrosion |
Abbreviated Journal |
Int. J. Corros. |
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2013 |
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Article ID 139798 |
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13 |
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The corrosion rates in the presence of some indole derivates, namely, 9H-pyrido[3,4-b]indole (norharmane) and 1-methyl-9H-pyrido[3,4-b]indole (harmane), as inhibitors of C38 steel corrosion inhibitor in 1 M HCl solution, were measured by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques, in the range of temperatures from 25 to 55 °C. Results obtained revealed that the organic compounds investigated have inhibiting properties for all temperatures. The inhibition was assumed to occur via adsorption of the indole molecules on the metal surface. Adsorption of indole derivates was found to follow the Langmuir isotherm. The apparent activation energies, enthalpies, and entropies of the dissolution process and the free energies and enthalpies for the adsorption process were determined by potentiodynamic polarization and electrochemical impedance. The fundamental thermodynamic functions were used to collect important information about indole inhibitory behaviour. © 2013 M. Lebrini et al. |
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Laboratoire Matériaux et Molécules en Milieu Amazonien, UAG-UMR ECOFOG, Campus Trou Biran, 97337 Cayenne, French Guiana |
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Export Date: 4 July 2013; Source: Scopus; Art. No.: 139798 |
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EcoFoG @ webmaster @ |
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495 |
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Zalamea, P.-C.; Sarmiento, C.; Stevenson, P.R.; Rodríguez, M.; Nicolini, E.; Heuret, P. |
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Effect of rainfall seasonality on the growth of Cecropia sciadophylla: Intra-annual variation in leaf production and node length |
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Journal Article |
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2013 |
Publication |
Journal of Tropical Ecology |
Abbreviated Journal |
J. Trop. Ecol. |
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29 |
Issue |
4 |
Pages |
361-365 |
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leaf phenology; Neotropics; pioneer plants; plant growth; plant morphology; rainfall seasonality; Urticaceae |
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Patterns of leaf production and leaf fall directly influence leaf area index and forest productivity. Here, we focused on Cecropia sciadophylla individuals inhabiting the extremes of the gradient in seasonality in rainfall at which C. sciadophylla occurs. In Colombia and French Guiana we compared the intra-annual variation in leaf production as well as the intra-annual fluctuation in internode length on a total of 69 saplings ranging in size from 1 to 2 m. The mean rate of leaf production was ~2 leaves mo -1 in both populations, and the rate of leaf production was constant throughout the year. Our results showed monthly variation in internode length and the number of live leaves per sapling in the seasonal habitat and variation only in internode length in the everwet habitat. Because the rate of leaf production is constant at both localities, the difference in number of live leaves per sapling at the seasonal site must reflect seasonal variation in leaf life span. We show that in Cecropia, internode length can serve as an indicator of precipitation seasonality. Finally an open question is whether leaf production in other pioneer species is also independent of climatic seasonal cues. This information could allow us to link growth and climate of secondary forest species and better understand how past and future climate can affect plant growth trajectories. © Cambridge University Press 2013. |
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INRA, UMR ECOFOG, Kourou F-97310, French Guiana |
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Export Date: 14 July 2013; Source: Scopus |
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no |
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EcoFoG @ webmaster @ |
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496 |
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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. |
| Title |
Hyperdominance in the Amazonian Tree Flora |
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Journal Article |
| Year |
2013 |
Publication |
Science |
Abbreviated Journal |
Science |
| Volume |
342 |
Issue |
6156 |
Pages |
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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507 |
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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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Journal Article |
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2013 |
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ESAIM: Probability and Statistics |
Abbreviated Journal |
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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EcoFoG @ webmaster @ |
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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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Journal Article |
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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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EcoFoG @ webmaster @ |
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523 |
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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 |
Abbreviated Journal |
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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EcoFoG @ webmaster @ |
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525 |
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