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Author Abedini, R.; Clair, B.; Pourtahmasi, K.; Laurans, F.; Arnould, O.
Title Cell wall thickening in developing tension wood of artificially bent poplar trees Type Journal Article
Year 2015 Publication IAWA Journal Abbreviated Journal IAWA Journal
Volume 36 Issue 1 Pages 44-57
Keywords developing xylem; Gelatinous layer; maturation stress; secondary wall layer; tree biomechanics
Abstract Trees can control their shape and resist gravity thanks to their ability to produce wood under tensile stress. This stress is known to be produced during the maturation of wood fibres but the mechanism of its generation remains unclear. This study focuses on the formation of the secondary wall in tension wood produced in artificially tilted poplar saplings. Thickness of secondary wall layer (SL) and gelatinous layer (GL) were measured from cambium to mature wood in several trees sampled at different times after tilting. Measurements on wood fibres produced before tilting show the progressive increase of secondary wall thickness during the growing season. After the tilting date, SL thickness decreased markedly from normal wood to tension wood while the total thickness increased compared to normal wood, with the development of a thick GL. However, even after GL formation, SL thickness continues to increase during the growing season. GL thickening was observed to be faster than SL thickening. The development of the unlignified GL is proposed to be a low cost, efficient strategy for a fast generation of tensile stress in broadleaved trees. © 2015 International Association of Wood Anatomists.
Address INRA, UR588 Amélioration, Génétique et Physiologie ForestièresOrléans, France
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Notes (down) Export Date: 17 April 2015 Approved no
Call Number EcoFoG @ webmaster @ Serial 596
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Author Tritsch, I.; Gond, V.; Oszwald, J.; Davy, D.; Grenand, P.
Title Territorial dynamics in the wayãpi and teko amerindian communities of the middle oyapock, camopi, French Guiana Type Journal Article
Year 2012 Publication Bois et Forets des Tropiques Abbreviated Journal Bois Forets Tropiques
Volume 66 Issue 311 Pages 49-61
Keywords Amerindian populations; French Guiana; Protected area; Slash-and-burn cultivation; System of natural resource use; Territorial management
Abstract Amerindian populations have been experiencing major socio-economic changes for several decades, in a context of rapid demographic growth. This article addresses the ways in which the Amerindian populations of French Guiana have adapted their land use and natural resource management systems to cope with the pressures exerted on their lands and lifestyles. The aim was to investigate the resilience of their systems for land and natural resource use. The concentration of Amerindian habitats around the town of Camopi, which is linked to the availability of health and school infrastructure and to efforts to promote a sedentary lifestyle, is a factor of increasing natural resource scarcity and social alienation. The system is adapting by fragmenting the Amerindian habitat into peripheral villages and extending farmlands along rivers to access to more space. These villages replicate patterns of spatial organisation that are similar to those found in traditional Wayãpi and Teko villages, except that habitation is sedentary, as families hope to have their villages equipped with at lEast drinking water and electrification. Habitat fragmentation is spatially limited by the time taken for daily journeys to school, and therefore by school bus services (dugout), which means that land use is effectively conditioned by services and infrasrtucture. Other living quarters are maintained at a distance from the village, so that the habitat is bi-local: families have a main home where services and infrastructure are available, and a secondary itinerant home further away, which is chosen according to the quality of farmland, the hunting yield of hunting resources, the history of the location and family networks. These distant homes are kept up by spending income from social assistance on transport. It's thus shown that these Amerindian systems for land and natural resource uses are highly adaptable, in that their sustainability is guaranteed by the reconstruction of a circular pattern of mobility in accordance with the intensity of resource use.
Address Ird Observatoire Hommes-Milieux Oyapock, Cnrs Guyane, 2, avenue Gustave Charlery, 97300 Cayenne, France
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Notes (down) Export Date: 17 April 2013; Source: Scopus; Language of Original Document: French; Correspondence Address: Tritsch, I.; Université des Antilles et de la Guyane/Cirad, Umr Écologie des forêts de Guyane, Campus agronomique de Kourou, 97310 Kourou, France Approved no
Call Number EcoFoG @ webmaster @ Serial 482
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Author Aubry-Kientz, M.; Rossi, V.; Wagner, F.; Herault, B.
Title Identifying climatic drivers of tropical forest dynamics Type Journal Article
Year 2015 Publication Biogeosciences Abbreviated Journal Biogeosciences
Volume 12 Issue 19 Pages 5583-5596
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Abstract In the context of climate change, identifying and then predicting the impacts of climatic drivers on tropical forest dynamics is becoming a matter of urgency. To look at these climate impacts, we used a coupled model of tropical tree growth and mortality, calibrated with forest dynamic data from the 20-year study site of Paracou, French Guiana, in order to introduce and test a set of climatic variables. Three major climatic drivers were identified through the variable selection procedure: drought, water saturation and temperature. Drought decreased annual growth and mortality rates, high precipitation increased mortality rates and high temperature decreased growth. Interactions between key functional traits, stature and climatic variables were investigated, showing best resistance to drought for trees with high wood density and for trees with small current diameters. Our results highlighted strong long-term impacts of climate variables on tropical forest dynamics, suggesting potential deep impacts of climate changes during the next century. © Author(s) 2015.
Address Remote Sensing Division, National Institute for Space Research-INPE, São José dos Campos, SP, Brazil
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Notes (down) Export Date: 16 October 2015 Approved no
Call Number EcoFoG @ webmaster @ Serial 631
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Author Dejean, A.; Ryder, S.; Bolton, B.; Compin, A.; Leponce, M.; Azémar, F.; Céréghino, R.; Orivel, J.; Corbara, B.
Title How territoriality and host-tree taxa determine the structure of ant mosaics Type Journal Article
Year 2015 Publication The Science of Nature Abbreviated Journal Sci Nat
Volume 102 Issue 33 Pages 1-9
Keywords Africa; Arboreal ants; Distribution; Host-tree selection; Rainforest canopies
Abstract Very large colonies of territorially dominant arboreal ants (TDAAs), whose territories are distributed in a mosaic pattern in the canopies of many tropical rainforests and tree crop plantations, have a generally positive impact on their host trees. We studied the canopy of an old Gabonese rainforest (ca 4.25 ha sampled, corresponding to 206 Blarge trees) at a stage just preceding forest maturity (the Caesalpinioideae dominated; the Burseraceae were abundant). The tree crowns sheltered colonies from 13 TDAAs plus a codominant species out of the 25 ant species recorded. By mapping the TDAAs' territories and using a null model cooccurrence analysis, we confirmed the existence of an ant mosaic. Thanks to a large sampling set and the use of the self-organizing map algorithm (SOM), we show that the distribution of the trees influences the structure of the ant mosaic, suggesting that each tree taxon attracts certain TDAA species rather than others. The SOMalso improved our knowledge of the TDAAs' ecological niches, showing that these ant species are ecologically distinct from each other based on their relationships with their supporting trees. Therefore, TDAAs should not systematically be placed in the same functional group even when they belong to the same genus.We conclude by reiterating that, in addition to the role played by TDAAs' territorial competition, host trees contribute to structuring ant mosaics through multiple factors, including host-plant selection by TDAAs, the age of the trees, the presence of extrafloral nectaries, and the taxa of the associated hemipterans. © Springer-Verlag Berlin Heidelberg 2015.
Address Université Clermont Auvergne, Université Blaise Pascal (LMGE), Clermont-Ferrand, France
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Notes (down) Export Date: 16 October 2015 Approved no
Call Number EcoFoG @ webmaster @ Serial 632
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Author Siefert, A.; Violle, C.; Chalmandrier, L.; Albert, C.H.; Taudiere, A.; Fajardo, A.; Aarssen, L.W.; Baraloto, C.; Carlucci, M.B.; Cianciaruso, M.V.; de L. Dantas, V.; de Bello, F.; Duarte, L.D.S.; Fonseca, C.R.; Freschet, G.T.; Gaucherand, S.; Gross, N.; Hikosaka, K.; Jackson, B.; Jung, V.; Kamiyama, C.; Katabuchi, M.; Kembel, S.W.; Kichenin, E.; Kraft, N.J.B.; Lagerström, A.; Bagousse-Pinguet, Y.L.; Li, Y.; Mason, N.; Messier, J.; Nakashizuka, T.; Overton, J.M.; Peltzer, D.A.; Pérez-Ramos, I.M.; Pillar, V.D.; Prentice, H.C.; Richardson, S.; Sasaki, T.; Schamp, B.S.; Schöb, C.; Shipley, B.; Sundqvist, M.; Sykes, M.T.; Vandewalle, M.; Wardle, D.A.
Title A global meta-analysis of the relative extent of intraspecific trait variation in plant communities Type Journal Article
Year 2015 Publication Ecology Letters Abbreviated Journal Ecology Letters
Volume 18 Issue 12 Pages 1406-1419
Keywords Community ecology; Functional diversity; Interspecific variation; Intraspecific variability; Leaf trait; Plant functional trait; Trait-based ecology
Abstract Recent studies have shown that accounting for intraspecific trait variation (ITV) may better address major questions in community ecology. However, a general picture of the relative extent of ITV compared to interspecific trait variation in plant communities is still missing. Here, we conducted a meta-analysis of the relative extent of ITV within and among plant communities worldwide, using a data set encompassing 629 communities (plots) and 36 functional traits. Overall, ITV accounted for 25% of the total trait variation within communities and 32% of the total trait variation among communities on average. The relative extent of ITV tended to be greater for whole-plant (e.g. plant height) vs. organ-level traits and for leaf chemical (e.g. leaf N and P concentration) vs. leaf morphological (e.g. leaf area and thickness) traits. The relative amount of ITV decreased with increasing species richness and spatial extent, but did not vary with plant growth form or climate. These results highlight global patterns in the relative importance of ITV in plant communities, providing practical guidelines for when researchers should include ITV in trait-based community and ecosystem studies. © 2015 John Wiley & Sons Ltd/CNRS.
Address Department of Physical Geography and Ecosystem Science, Lund University, Sölvegatan 12, Lund, Sweden
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Notes (down) Export Date: 16 November 2015 Approved no
Call Number EcoFoG @ webmaster @ Serial 637
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Author Richard-Hansen, C.; Jaouen, G.; Denis, T.; Brunaux, O.; Marcon, E.; Guitet, S.
Title Landscape patterns influence communities of medium-to large-bodied vertebrates in undisturbed terra firme forests of French Guiana Type Journal Article
Year 2015 Publication Journal of Tropical Ecology Abbreviated Journal Journal of Tropical Ecology
Volume 31 Issue 5 Pages 423-436
Keywords Animal communities; diversity; environmental heterogeneity; French Guiana; landscape ecology; species-habitat association
Abstract Whereas broad-scale Amazonian forest types have been shown to influence the structure of the communities of medium-to large-bodied vertebrates, their natural heterogeneity at smaller scale or within the terra firme forests remains poorly described and understood. Diversity indices of such communities and the relative abundance of the 21 most commonly observed species were compared from standardized line-transect data across 25 study sites distributed in undisturbed forests in French Guiana. We first assessed the relevance of a forest typology based on geomorphological landscapes to explain the observed heterogeneity. As previously found for tree beta-diversity patterns, this new typology proved to be a non-negligible factor underlying the beta diversity of the communities of medium-to large bodied vertebrates in French Guianan terra firme forests. Although the species studied are almost ubiquitous across the region, they exhibited habitat preferences through significant variation in abundance and in their association index with the different landscape types. As terra firme forests represent more than 90% of the Amazon basin, characterizing their heterogeneity-including faunal communities-is a major challenge in neotropical forest ecology. © 2015 Cambridge University Press.
Address ONCFS, EcoFoG, Kourou Cedex, France
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Notes (down) Export Date: 16 November 2015 Approved no
Call Number EcoFoG @ webmaster @ Serial 638
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Author Soong, J.L.; Marañon-Jimenez, S.; Cotrufo, M.F.; Boeckx, P.; Bodé, S.; Guenet, B.; Peñuelas, J.; Richter, A.; Stahl, C.; Verbruggen, E.; Janssens, I.A.
Title Soil microbial CNP and respiration responses to organic matter and nutrient additions: Evidence from a tropical soil incubation Type Journal Article
Year 2018 Publication Soil Biology and Biochemistry Abbreviated Journal
Volume 122 Issue Pages 141-149
Keywords 13c; Cnp; Microbial stoichiometry; Priming; Soil respiration; Tropics
Abstract Soil nutrient availability has a strong influence on the fate of soil carbon (C) during microbial decomposition, contributing to Earth's C balance. While nutrient availability itself can impact microbial physiology and C partitioning between biomass and respiration during soil organic matter decomposition, the availability of labile C inputs may mediate the response of microorganisms to nutrient additions. As soil organic matter is decomposed, microorganisms retain or release C, nitrogen (N) or phosphorus (P) to maintain a stoichiometric balance. Although the concept of a microbial stoichiometric homeostasis has previously been proposed, microbial biomass CNP ratios are not static, and this may have very relevant implications for microbial physiological activities. Here, we tested the hypothesis that N, P and potassium (K) nutrient additions impact C cycling in a tropical soil due to microbial stoichiometric constraints to growth and respiration, and that the availability of energy-rich labile organic matter in the soil (i.e. leaf litter) mediates the response to nutrient addition. We incubated tropical soil from French Guiana with a 13C labeled leaf litter addition and with mineral nutrient additions of +K, +N, +NK, +PK and +NPK for 30 days. We found that litter additions led to a ten-fold increase in microbial respiration and a doubling of microbial biomass C, along with greater microbial N and P content. We found some evidence that P additions increased soil CO2 fluxes. Additionally, we found microbial biomass CP and NP ratios varied more widely than CN in response to nutrient and organic matter additions, with important implications for the role of microorganisms in C cycling. The addition of litter did not prime soil organic matter decomposition, except in combination with +NK fertilization, indicating possible P-mining of soil organic matter in this P-poor tropical soil. Together, these results point toward an ultimate labile organic substrate limitation of soil microorganisms in this tropical soil, but also indicate a complex interaction between C, N, P and K availability. This highlights the difference between microbial C cycling responses to N, P, or K additions in the tropics and explains why coupled C, N and P cycle modeling efforts cannot rely on strict microbial stoichiometric homeostasis as an underlying assumption.
Address INRA, UMR Ecology of Guiana Forests (Ecofog), AgroParisTech, Cirad, CNRS, Université de Guyane, Université des Antilles, Kourou, France
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Notes (down) Export Date: 16 May 2018 Approved no
Call Number EcoFoG @ webmaster @ Serial 804
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Author Baraloto, C.; Molto, Q.; Rabaud, S.; Herault, B.; Valencia, R.; Blanc, L.; Fine, P.V.A.; Thompson, J.
Title Rapid simultaneous estimation of aboveground biomass and tree diversity across neotropical forests: A comparison of field inventory methods Type Journal Article
Year 2013 Publication Biotropica Abbreviated Journal Biotropica
Volume 45 Issue 3 Pages 288-298
Keywords Biodiversity assessment; carbon stocks; Monitoring; Permanent plot; Survey; Tropical rain forest
Abstract A standardized rapid inventory method providing information on both tree species diversity and aboveground carbon stocks in tropical forests will be an important tool for evaluating efforts to conserve biodiversity and to estimate the carbon emissions that result from deforestation and degradation (REDD). Herein, we contrast five common plot methods differing in shape, size, and effort requirements to estimate tree diversity and aboveground tree biomass (AGB). We simulated the methods across six Neotropical forest sites that represent a broad gradient in forest structure, tree species richness, and floristic composition, and we assessed the relative performance of methods by evaluating the bias and precision of their estimates of AGB and tree diversity. For a given sample of forest area, a 'several small' (< 1 ha) sampling strategy led to a smaller coefficient of variation (CV) in the estimate of AGB than a 'few large' one. The effort (person-days) required to achieve an accurate AGB estimate (< 10% CV), however, was greater for the smallest plots (0.1 ha) than for a compromise approach using 0.5 ha modified Gentry plots, which proved to be the most efficient method to estimate AGB across all forest types. Gentry plots were also the most efficient at providing accurate estimates of tree diversity (< 10% CV of Hill number). We recommend the use of the 0.5 ha modified Gentry plot method in future rapid inventories, and we discuss a set of criteria that should inform any choice of inventory method. © 2012 The Author(s) Journal compilation © 2012 by The Association for Tropical Biology and Conservation.
Address Centre for Ecology and Hydrology, Bush Estate, Penicuik, Midlothian, EH26 0QB, United Kingdom
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Notes (down) Export Date: 16 May 2013; Source: Scopus; Coden: Btroa; :doi 10.1111/btp.12006; Language of Original Document: English; Correspondence Address: Baraloto, C.; INRA, UMR 'Ecologie des Forêts de Guyane', 97387, Kourou Cedex, French Guiana; email: chris.baraloto@ecofog.gf Approved no
Call Number EcoFoG @ webmaster @ Serial 485
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Author Privet, K.; Vedel, V.; Fortunel, C.; Orivel, J.; Martinez, Q.; Cerdan, A.; Baraloto, C.; Pétillon, J.
Title Relative effciency of pitfall trapping vs. nocturnal hand collecting in assessing soil-dwelling spider diversity along a structural gradient of neotropical habitats Type Journal Article
Year 2020 Publication Diversity Abbreviated Journal Diversity
Volume 12 Issue 2 Pages 81
Keywords Araneae; Diversity indices; Functional diversity; Guiana shield; Sampling methods; Species richness; Turnover; Araneae
Abstract Assessing spider diversity remains a great challenge, especially in tropical habitats where dozens of species can locally co-occur. Pitfall trapping is one of the most widely used techniques to collect spiders, but it suffers from several biases, and its accuracy likely varies with habitat complexity. In this study, we compared the efficiency of passive pitfall trapping versus active nocturnal hand collecting (\"HC) to capture low understory-dwelling spider taxonomical (morpho-species) and functional (hunting guilds) diversity along a structural gradient of habitats in French Guiana. We focused on four habitats describing a structural gradient: garden to the orchard to the forest edge to the undisturbed forest. Overall, estimated morpho-species richness and composition did not vary consistently between habitats, but abundances of ground-hunting spiders decreased significantly with increasing habitat complexity. We found habitat-dependence differences in taxonomic diversity between sampling strategies: NHC revealed higher diversity in the orchard, whereas pitfalls resulted in higher diversity in the forest. Species turnover resulted in high dissimilarity in species composition between habitats using either method. This study shows how pitfall trapping is influenced by habitat structure, rendering this sampling method incomplete for complex, tropical environments. However, pitfall traps remain a valuable component of inventories because they sample distinct assemblage of spiders. © 2020 by the authors.
Address International Center for Tropical Botany, Department of Biological Sciences, Florida International University, 11200 S.W. 8th Street, Miami, FL 33199, United States
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ISSN 14242818 (Issn) ISBN Medium
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Notes (down) Export Date: 16 March 2020; Correspondence Address: Privet, K.; CNRS, Ecobio (Ecosystèmes, biodiversité, évolution), Université de RennesFrance; email: kprivet@hotmail.fr Approved no
Call Number EcoFoG @ webmaster @ Serial 923
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Author Denis, T.; Richard-Hansen, C.; Brunaux, O.; Guitet, S.; Hérault, B.
Title Birds of a feather flock together: Functionally similar vertebrates positively co-occur in Guianan forests Type Journal Article
Year 2019 Publication Ecosphere Abbreviated Journal Ecosphere
Volume 10 Issue 3 Pages e02566
Keywords activity matching; birds; Guiana Shield; information exchange; mammals; mixed-species associations; mutualism; terra firme rainforests
Abstract Medium- and large-sized vertebrates play a key role in shaping overall forest functioning. Despite this, vertebrate interactions, from competition to mutualism, remain poorly studied, even though these interactions should be taken into account in our conservation and management strategies. Thus, we tackled the question of vertebrate co-occurrence in tropical rainforests: Are (negative or positive) co-occurrences dependent on forest structure and composition? and Are these co-occurrences linked to functional species similarity? We recorded the occurrence of 21 medium- and large-sized vertebrates in 19 French Guianan locations in which a large set of forest structure and composition descriptors were collected. We used a probabilistic model to look for co-occurrences at different spatial scales, and species pairwise co-occurrences were then compared to those generated solely on the basis of forest structure and composition. We then quantified the co-occurrence strength between pairwise species dyads and determined whether they relied on species functional similarity, controlling for the environmental effects. We found that positive co-occurrences vastly outnumbered negative co-occurrences, were only partly shaped by the local environment, and were closely linked to species functional similarity. Thus, groups of species sharing similar functional traits are more prone to co-occur, highlighting the key role of functional redundancy in structuring species assemblages. We discuss how positive interactions could generate the predominance of positive co-occurrences in oligotrophic terra firme (unflooded) forests when resources are scarce and dispersed in dry season. Finally, we identified functional groups based on co-occurrence strength and suggested that frugivory/granivory and body size are of primary importance in species interactions in Neotropical vertebrate communities. © 2019 The Authors.
Address INPHB, Institut National Polytechnique Félix Houphouët-Boigny, Yamoussoukro, Cote d'Ivoire
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Notes (down) Export Date: 16 March 2020; Correspondence Address: Denis, T.; Office National de la Chasse et de la Faune Sauvage, UMR EcoFoG (AgroParisTech, Cirad, CNRS, INRA, Université des Antilles, Université de Guyane)France; email: thomas.denis@ecofog.gf Approved no
Call Number EcoFoG @ webmaster @ Serial 924
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