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Author Leroy, C.; Corbara, B.; Dezerald, O.; Trzcinski, M.K.; Carrias, J.-F.; Dejean, A.; Céréghino, R.
Title What drives detrital decomposition in neotropical tank bromeliads? Type Journal Article
Year 2017 Publication Hydrobiologia Abbreviated Journal Hydrobiologia
Volume 802 Issue 1 Pages (down) 85-95
Keywords Context dependency; Ecosystem function; Food webs; Leaf litter; Phytotelmata; Rainforest
Abstract Decomposition experiments that control leaf litter species across environments help to disentangle the roles of litter traits and consumer diversity, but once we account for leaf litter effects, they tell us little about the variance in decomposition explained by shifts in environmental conditions versus food-web structure. We evaluated how habitat, food-web structure, leaf litter species, and the interactions between these factors affect litter mass loss in a neotropical ecosystem. We used water-filled bromeliads to conduct a reciprocal transplant experiment of two litter species between an open and a forested habitat in French Guiana, and coarse- and fine-mesh enclosures embedded within bromeliads to exclude invertebrates or allow them to colonize leaf litter disks. Soft Melastomataceae leaves decomposed faster in their home habitat, whereas tough Eperua leaves decomposed equally in both habitats. Bacterial densities did not differ significantly between the two habitats. Significant shifts in the identity and biomass of invertebrate detritivores across habitats did not generate differences in leaf litter decomposition, which was essentially microbial. Despite the obvious effects of habitats on food-web structure, ecosystem processes are not necessarily affected. Our results pose the question of when does environmental determinism matter for ecosystem functions, and when does it not. © 2017, Springer International Publishing Switzerland.
Address IRD – UMR AMAP, Campus agronomique, BP 316, Kourou Cedex, France
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Notes Export Date: 18 December 2017 Approved no
Call Number EcoFoG @ webmaster @ Serial 775
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Author Pétillon, J.; Leroy, B.; Djoudi, E.A.; Vedel, V.
Title Small and large spatial scale coexistence of ctenid spiders in a neotropical forest (French Guiana) Type Journal Article
Year 2018 Publication Tropical Zoology Abbreviated Journal
Volume 31 Issue 2 Pages (down) 85-98
Keywords Araneae; flooding; Guianese shield; inselberg; juveniles
Abstract While spiders constitute the most abundant and diverse arthropods in many habitats, they remained under-studied, especially in tropical rainforests. The goal of this study is to assess the spatial distribution of the spider family Ctenidae by assessing associations of species diversity and population traits among different habitat conditions. Fieldwork was carried out during 2013 in habitats varying in flooding frequency (plateau vs. flooded forest) and elevation (inselberg vs. lowland) in the Nouragues National Natural Reserve, French Guiana. Assemblage composition, population structure, and trait measurements of one dominant species were assessed using hand collection in replicated quadrats. We found strong effects on ctenid assemblages attributable to both elevation and flooding, with changes in relative abundance of species among habitats, but few correlated densities between species. At the population level, main differences in species distribution between and within habitats were detected only when juveniles were taken into account. No effect of elevation was found on the measurements of traits of the dominant species, but legs were proportionally shorter in flooded habitats, suggesting reduced active dispersal in these habitats. Our study highlights the value of complementary of measures of diversity and traits at different biological scales in Ctenidae.
Address UMR CNRS 8175 Ecologie des Forêts de Guyane, Université Antilles-Guyane, Kourou Cedex, Guyane Française, France
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Notes Export Date: 23 April 2018 Approved no
Call Number EcoFoG @ webmaster @ Serial 800
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Author Courtois, E.A.; Baraloto, C.; Timothy Paine, C.E.; Petronelli, P.; Blandinieres, P.-A.; Stien, D.; Houel, E.; Bessiere, J.-M.; Chave, J.
Title Differences in volatile terpene composition between the bark and leaves of tropical tree species Type Journal Article
Year 2012 Publication Phytochemistry Abbreviated Journal Phytochemistry
Volume 82 Issue Pages (down) 81-88
Keywords French Guiana; Herbivory; Optimal defense theory; Secondary metabolites; Wood
Abstract Volatile terpenes are among the most diverse class of defensive compounds in plants, and they are implicated in both direct and indirect defense against herbivores. In terpenes, both the quantity and the diversity of compounds appear to increase the efficiency of defense as a diverse blend of compounds provides a more efficient protection against a broader range of herbivores and limits the chances that an enemy evolves resistance. Theory predicts that plant defensive compounds should be allocated differentially among tissues according to the value of the tissue, its cost of construction and the herbivore pressure on it. We collected volatile terpenes from bark and leaves of 178 individual tree belonging to 55 angiosperm species in French Guiana and compare the kind, amount, and diversity of compounds in these tissues. We hypothesized that in woody plants, the outermost part of the trunk should hold a more diverse blend of volatile terpenes. Additionally, as herbivore communities associated with the leaves is different to the one associated with the bark, we also hypothesized that terpene blends should be distinct in the bark vs. the leaves of a given species. We found that the mixture of volatile terpenes released by bark is different and more diverse than that released by leaves, both in monoterpenes and sesquiterpenes. This supports our hypothesis and further suggests that the emission of terpenes by the bark should be more important for trunk defense than previously thought.
Address Station d'Écologie Expérimentale du CNRS Moulis, USR 2936, 2 route du CNRS, 09200 Moulis, France
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ISSN 00319422 (Issn) ISBN Medium
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Notes Export Date: 4 September 2012; Source: Scopus; Coden: Pytca; doi: 10.1016/j.phytochem.2012.07.003; Language of Original Document: English; Correspondence Address: Courtois, E.A.; Station d'Écologie Expérimentale du CNRS Moulis, USR 2936, 2 route du CNRS, 09200 Moulis, France; email: courtoiselodie@gmail.com Approved no
Call Number EcoFoG @ webmaster @ Serial 425
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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 (down) 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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Publisher Mdpi Ag Place of Publication Editor
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ISSN 14242818 (Issn) ISBN Medium
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Notes 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 Vacher, Corinne ; Castagneyrol, Bastien ; Jousselin, Emmanuelle ; Schimann, Heidy
Title Trees and Insects Have Microbiomes: Consequences for Forest Health and Management Type Journal Article
Year 2021 Publication Current Forestry Reports Abbreviated Journal
Volume 7 Issue 2 Pages (down) 81-96
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Abstract Purpose of Review Forest research has shown for a long time that microorganisms influence tree-insect interactions, but the complexity of microbial communities, as well as the holobiont nature of both trees and insect herbivores, has only recently been taken fully into account by forest entomologists and ecologists. In this article, we review recent findings on the effects of tree-insect-microbiome interactions on the health of tree individuals and discuss whether and how knowledge about tree and insect microbiomes could be integrated into forest health management strategies. We then examine the effects tree-insect-microbiome interactions on forest biodiversity and regeneration, highlighting gaps in our knowledge at the ecosystem scale. Recent Findings Multiple studies show that herbivore damage in forest ecosystems is clearly influenced by tripartite interactions between trees, insects and their microbiomes. Recent research on the plant microbiome indicates that microbiomes of planted trees could be managed at several stages of production, from seed orchards to mature forests, to improve the resistance of forest plantations to insect pests. Therefore, the tree microbiome could potentially be fully integrated into forest health management strategies. To achieve this aim, future studies will have to combine, as has long been done in forest research, holistic goals with reductionist approaches. Efforts should be made to improve our understanding of how microbial fluxes between trees and insects determine the health of forest ecosystems, and to decipher the underlying mechanisms, through the development of experimental systems in which microbial communities can be manipulated. Knowledge about tree-insect-microbiome interactions should then be integrated into spatial models of forest dynamics to move from small-scale mechanisms to forest ecosystem-scale predictions.
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Call Number EcoFoG @ webmaster @ Serial 1059
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Author Tahiri, A.; Amissa Adima, A.; Adjé, F.A.; Amusant, N.
Title Pesticide effects and screening of extracts of Azadirachta Indica (A.) Juss. on the Macrotermes bellicosus rambur termite Type Journal Article
Year 2011 Publication Bois et Forets des Tropiques Abbreviated Journal Effet pesticide et screening des extraits de Azadirachta indica (A.) Juss. sur le termite Macroterme
Volume 65 Issue 310 Pages (down) 79-88
Keywords Azadirachta indica; Pesticide properties; Phytochemical screening; Termite
Abstract To recommend applications in the field of a naturally insecticide plant substance as an alternative to chemical control against termite attacks, several important prerequisites need to be satisfied to ensure its effectiveness. The toxicity, lethal dose, mode of action, persistence of insecticide effect and chemical composition of total aqueous, alcohol and hexane extracts of the leaves and seeds of the neem tree, Azadirachta indica, were tested with the Macrotermes bellicosus termite. The extracts were found to be highly toxic to termites on contact, killing the entire population tested. The insecticide effect of the extracts persisted from 2.4 to 4.2 days. The aqueous and hexane extracts were the most toxic (LD50 0.422±0.018 to 4,466±0,162 mg/l). Contact and inhalation were both essential to their effectiveness. The aqueous extract of seeds, which is the most active, is also capable of being transferred through the colony during social tasks. However, it seems to have an anti-appetent effect on termites and does not act by ingestion. It contains phenol compounds (tannins and flavonoids) and saponins. The hexane extract of seeds is oily and contains 11 fatty acids as well as terpenoids, flavonoids and saponins.
Address Cirad Laboratoire de Chimie du Bois, 34398 Montpellier Cedex 5, France
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Notes Export Date: 20 November 2012; Source: Scopus Approved no
Call Number EcoFoG @ webmaster @ Serial 447
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Author Fortunel, C.; Ruelle, J.; Beauchene, J.; Fine, P.V.A.; Baraloto, C.
Title Wood specific gravity and anatomy of branches and roots in 113 Amazonian rainforest tree species across environmental gradients Type Journal Article
Year 2014 Publication New Phytologist Abbreviated Journal New Phytol.
Volume 202 Issue 1 Pages (down) 79-94
Keywords Amazonian forests; Branch; Environmental gradients; Neotropical trees; Root; Wood anatomical traits; Wood density; Wood functions
Abstract Wood specific gravity (WSG) is a strong predictor of tree performance across environmental gradients. Yet it remains unclear how anatomical elements linked to different wood functions contribute to variation in WSG in branches and roots across tropical forests. We examined WSG and wood anatomy in white sand, clay terra firme and seasonally flooded forests in French Guiana, spanning broad environmental gradients found throughout Amazonia. We measured 15 traits relating to branches and small woody roots in 113 species representing the 15 most abundant species in each habitat and representative species from seven monophyletic lineages occurring in all habitats. Fiber traits appear to be major determinants of WSG, independent of vessel traits, in branches and roots. Fiber traits and branch and root WSG increased from seasonally flooded species to clay terra firme species and lastly to white sand species. Branch and root wood traits were strongly phylogenetically constrained. Lineages differed in wood design, but exhibited similar variation in wood structure across habitats. We conclude that tropical trees can invest differently in support and transport to respond to environmental conditions. Wind disturbance and drought stress represent significant filters driving tree distribution of Amazonian forests; hence we suggest that biophysical explanations should receive more attention. © 2013 New Phytologist Trust.
Address Department of Biology, University of Florida, Gainesville, FL, 32611, United States
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Notes Export Date: 10 March 2014; Source: Scopus; Coden: Nepha; Language of Original Document: English; Correspondence Address: Fortunel, C.; INRA, UMR Ecologie des Forêts de Guyane, BP 709, Kourou Cedex, 97387, France; email: claire.fortunel@ecofog.gf; Funding Details: DEB-0743103, NSF, National Science Foundation; Funding Details: DEB-0743800, NSF, National Science Foundation Approved no
Call Number EcoFoG @ webmaster @ Serial 531
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Author Laurans, M.; Herault, B.; Vieilledent, G.; Vincent, G.
Title Vertical stratification reduces competition for light in dense tropical forests Type Journal Article
Year 2014 Publication Forest Ecology and Management Abbreviated Journal For. Ecol. Manage.
Volume 329 Issue Pages (down) 79-88
Keywords Adult stature; French Guiana; Hierarchical bayesian model; Local crowding; Niche partitioning; Bayesian networks; Growth rate; Adult stature; French Guiana; Hierarchical Bayesian modeling; Local crowding; Niche partitioning; Reforestation
Abstract Differential growth response to light level is widely accepted as a potential mechanism for maintaining tree species richness in tropical forests. The position of tree species in the hierarchy of the canopy is considered an important indicator of species light capture and growth strategy. Paradoxically, the relative importance of species identity and competition for light in determining individual tree growth is poorly documented at the adult stage. In this study, we used a hierarchical Bayesian model to quantify the overall importance of species identity, light and belowground competition as determinants of tree growth in French Guiana tropical forest. Light competitive status is assessed by a crown exposure score and below ground competition is estimated from local crowding. We examined species sensitivity to both types of competition in relation to adult stature. Our results are based on annual diameter increments of more than 13,510 stems from 282 species monitored over 10years. Mean annual growth rate was 0.11cmy-1 with species identity explaining 35% of the individual variation in growth rate. Crown exposure and local crowding explained 3.5% and 2.4% of the variation in growth rate, respectively. Predicted changes in growth rate as crown exposure (resp. local crowding) index changed from lower to upper interquartile level was 0.03cmy-1 (resp. 0.02cmy-1). Species sensitivity to crown exposure and to local crowding were positively correlated (i) with predicted growth rate at high-light standardized conditions and (ii) with adult stature.This vertical niche partitioning is invoked to explain the limited contribution made by level of light competition for predicting individual tropical tree growth as the community-level response is dominated by the abundance of small-statured species with low sensitivity to light level.Light appears to drive the stem growth rate of tropical trees through species differentiation more than through individual tree growth limitation. This vertical stratification complements the previously reported regeneration niche and together these provide evidence for light niche partitioning in the three-dimensional space of tropical forests. © 2014 Elsevier B.V.
Address IRD, UMR AMAP, TA A-51/PS1, Bd de la Lironde, 34398 Montpellier Cedex 5, France
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Publisher Elsevier Place of Publication Editor
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Notes Export Date: 30 July 2014; Coden: Fecmd; Correspondence Address: Laurans, M.; CIRAD, UMR AMAP, TA A-51/PS1, Bd de la Lironde, 34398 Montpellier Cedex 5, France; email: laurans@cirad.fr Approved no
Call Number EcoFoG @ webmaster @ Serial 551
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Author Levionnois, Sébastien ; Ziegler, Camille ; Heuret, Patrick ; Jansen, Steven ; Stahl, Clément ; Calvet, Emma ; Goret, Jean-Yves ; Bonal, Damien ; Coste, Sabrina
Title Is vulnerability segmentation at the leaf‑stem transition a drought resistance mechanism? A theoretical test with a trait‑based model for Neotropical canopy tree species Type Journal Article
Year 2021 Publication Annals of Forest Science Abbreviated Journal
Volume 78 Issue 4 Pages (down) 78-87
Keywords Neotropics, bark, canopy, capacitance, drought, drought tolerance, embolism, leaves, models, transpiration, trees, tropical rain forests, xylem
Abstract Leaf-stem vulnerability segmentation predicts lower xylem embolism resistance in leaves than stem. However, although it has been intensively investigated these past decades, the extent to which vulnerability segmentation promotes drought resistance is not well understood. Based on a trait-based model, this study theoretically supports that vulnerability segmentation enhances shoot desiccation time across 18 Neotropical tree species. CONTEXT: Leaf-stem vulnerability segmentation predicts lower xylem embolism resistance in leaves than stems thereby preserving expensive organs such as branches or the trunk. Although vulnerability segmentation has been intensively investigated these past decades to test its consistency across species, the extent to which vulnerability segmentation promotes drought resistance is not well understood. AIMS: We investigated the theoretical impact of the degree of vulnerability segmentation on shoot desiccation time estimated with a simple trait-based model. METHODS: We combined data from 18 tropical rainforest canopy tree species on embolism resistance of stem xylem (flow-centrifugation technique) and leaves (optical visualisation method). Measured water loss under minimum leaf and bark conductance, leaf and stem capacitance, and leaf-to-bark area ratio allowed us to calculate a theoretical shoot desiccation time (tcᵣᵢₜ). RESULTS: Large degrees of vulnerability segmentation strongly enhanced the theoretical shoot desiccation time, suggesting vulnerability segmentation to be an efficient drought resistance mechanism for half of the studied species. The difference between leaf and bark area, rather than the minimum leaf and bark conductance, determined the drastic reduction of total transpiration by segmentation during severe drought. CONCLUSION: Our study strongly suggests that vulnerability segmentation is an important drought resistance mechanism that should be better taken into account when investigating plant drought resistance and modelling vegetation. We discuss future directions for improving model assumptions with empirical measures, such as changes in total shoot transpiration after leaf xylem embolism.
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Call Number EcoFoG @ webmaster @ Serial 1034
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Author Baraloto, C.; Ferreira, E.; Rockwell, C.; Walthier, F.
Title Limitations and Applications of Parataxonomy for Community Forest Management in Southwestern Amazonia Type Journal Article
Year 2007 Publication Ethnobotany Research & Applications Abbreviated Journal
Volume 5 Issue Pages (down) 77-84
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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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Notes 2008; Limitations and Applications of Parataxonomy for Community Forest Management in Southwestern Amazonia Approved no
Call Number EcoFoG @ eric.marcon @ 14 Serial 214
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