toggle visibility Search & Display Options

Select All    Deselect All
 |   | 
Details
   print
  Records Links
Author Levionnois, S.; Coste, S.; Nicolini, E.; Stahl, C.; Morel, H.; Heuret, P. url  doi
openurl 
  Title Scaling of petiole anatomies, mechanics and vasculatures with leaf size in the widespread Neotropical pioneer tree species Cecropia obtusa Trécul (Urticaceae) Type Journal Article
  Year 2020 Publication Tree physiology Abbreviated Journal Tree Physiol.  
  Volume 40 Issue 2 Pages (down) 245-258  
  Keywords allometry; leaf size; petiole anatomy; scaling; theoretical hydraulic conductivity; vessel widening; xylem  
  Abstract Although the leaf economic spectrum has deepened our understanding of leaf trait variability, little is known about how leaf traits scale with leaf area. This uncertainty has resulted in the assumption that leaf traits should vary by keeping the same pace of variation with increases in leaf area across the leaf size range. We evaluated the scaling of morphological, tissue-surface and vascular traits with overall leaf area, and the functional significance of such scaling. We examined 1,271 leaves for morphological traits, and 124 leaves for anatomical and hydraulic traits, from 38 trees of Cecropia obtusa Trécul (Urticaceae) in French Guiana. Cecropia is a Neotropical genus of pioneer trees that can exhibit large laminas (0.4 m2 for C. obtusa), with leaf size ranging by two orders of magnitude. We measured (i) tissue fractions within petioles and their second moment of area, (ii) theoretical xylem hydraulic efficiency of petioles and (iii) the extent of leaf vessel widening within the hydraulic path. We found that different scaling of morphological trait variability allows for optimisation of lamina display among larger leaves, especially the positive allometric relationship between lamina area and petiole cross-sectional area. Increasing the fraction of pith is a key factor that increases the geometrical effect of supportive tissues on mechanical rigidity and thereby increases carbon-use efficiency. We found that increasing xylem hydraulic efficiency with vessel size results in lower leaf lamina area: xylem ratios, which also results in potential carbon savings for large leaves. We found that the vessel widening is consistent with hydraulic optimisation models. Leaf size variability modifies scaling of leaf traits in this large-leaved species. © The Author(s) 2020. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permission@oup.com.  
  Address UMR AMAP, CIRAD, CNRS, IRD, Université de Montpellier, Montpellier, 34398, France  
  Corporate Author Thesis  
  Publisher NLM (Medline) Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 17584469 (Issn) ISBN Medium  
  Area Expedition Conference  
  Notes Export Date: 16 March 2020 Approved no  
  Call Number EcoFoG @ webmaster @ Serial 921  
Permanent link to this record
 

 
Author Herault, B.; Beauchene, J.; Muller, F.; Wagner, F.; Baraloto, C.; Blanc, L.; Martin, J.M. openurl 
  Title Modeling decay rates of dead wood in a neotropical forest Type Journal Article
  Year 2010 Publication Oecologia Abbreviated Journal Oecologia  
  Volume 164 Issue 1 Pages (down) 243-251  
  Keywords Amazonia; Carbon cycle; Decomposition; Selective logging; Rainforest; Coarse woody debris  
  Abstract Variation of dead wood decay rates among tropical trees remains one source of uncertainty in global models of the carbon cycle. Taking advantage of a broad forest plot network surveyed for tree mortality over a 23-year period, we measured the remaining fraction of boles from 367 dead trees from 26 neotropical species widely varying in wood density (0.23-1.24 g cm(-3)) and tree circumference at death time (31.5-272.0 cm). We modeled decay rates within a Bayesian framework assuming a first order differential equation to model the decomposition process and tested for the effects of forest management (selective logging vs. unexploited), of mode of death (standing vs. downed) and of topographical levels (bottomlands vs. hillsides vs. hilltops) on wood decay rates. The general decay model predicts the observed remaining fraction of dead wood (R (2) = 60%) with only two biological predictors: tree circumference at death time and wood specific density. Neither selective logging nor local topography had a differential effect on wood decay rates. Including the mode of death into the model revealed that standing dead trees decomposed faster than downed dead trees, but the gain of model accuracy remains rather marginal. Overall, these results suggest that the release of carbon from tropical dead trees to the atmosphere can be simply estimated using tree circumference at death time and wood density.  
  Address [Herault, Bruno; Wagner, Fabien; Martin, Jean-Michel] Univ Antilles Guyane, UMR EcoFoG, F-97387 Kourou, France, Email: bruno.herault@ecofog.gf  
  Corporate Author Thesis  
  Publisher SPRINGER Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0029-8549 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000280962200023 Approved no  
  Call Number EcoFoG @ eric.marcon @ Serial 45  
Permanent link to this record
 

 
Author Lang, G.; Marcon, E.; Puech, F. doi  openurl
  Title Distance-based measures of spatial concentration: introducing a relative density function Type Journal Article
  Year 2020 Publication Annals of Regional Science Abbreviated Journal Ann. Reg. Sci.  
  Volume 64 Issue 2 Pages (down) 243-265  
  Keywords Agglomeration; Aggregation; Economic geography; Point patterns; Spatial concentration; accuracy assessment; econometrics; economic activity; economic geography; industrial agglomeration; industrial location; location decision; spatial analysis; spatial distribution  
  Abstract For more than a decade, distance-based methods have been widely employed and constantly improved in spatial economics. These methods are a very useful tool for accurately evaluating the spatial distribution of economic activity. We introduce a new distance-based statistical measure for evaluating the spatial concentration of industries. The m function is the first relative density function to be proposed in economics. This tool supplements the typology of distance-based methods recently drawn up by Marcon and Puech (J Econ Geogr 3(4):409–428, 2003). By considering several simulated and real examples, we show the advantages and the limits of the m function for detecting spatial structures in economics. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.  
  Address RITM, Univ. Paris-Sud, Université Paris-Saclay and CREST, Sceaux, France  
  Corporate Author Thesis  
  Publisher Springer Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 05701864 (Issn) ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number EcoFoG @ webmaster @ Serial 976  
Permanent link to this record
 

 
Author Barantal, S.; Roy, J.; Fromin, N.; Schimann, H.; Hattenschwiler, S. openurl 
  Title Long-term presence of tree species but not chemical diversity affect litter mixture effects on decomposition in a neotropical rainforest Type Journal Article
  Year 2011 Publication Oecologia Abbreviated Journal Oecologia  
  Volume 167 Issue 1 Pages (down) 241-252  
  Keywords Amazonian rainforest; Chemical diversity; Decomposition; Functional diversity indices; Litter traits  
  Abstract Plant litter diversity effects on decomposition rates are frequently reported, but with a strong bias towards temperate ecosystems. Altered decomposition and nutrient recycling with changing litter diversity may be particularly important in tree species-rich tropical rainforests on nutrient-poor soils. Using 28 different mixtures of leaf litter from 16 Amazonian rainforest tree species, we tested the hypothesis that litter mixture effects on decomposition increase with increasing functional litter diversity. Litter mixtures and all single litter species were exposed in the field for 9 months using custom-made microcosms with soil fauna access. In order to test the hypothesis that the long-term presence of tree species contributing to the litter mixtures increases mixture effects on decomposition, microcosms were installed in a plantation at sites including the respective tree species composition and in a nearby natural forest where these tree species are absent. We found that mixture decomposition deviated from predictions based on single species, with predominantly synergistic effects. Functional litter diversity, defined as either richness, evenness, or divergence based on a wide range of chemical traits, did not explain the observed litter mixture effects. However, synergistic effects in litter mixtures increased with the long-term presence of tree species contributing to these mixtures as the home field advantage hypothesis assumes. Our data suggest that complementarity effects on mixed litter decomposition may emerge through long-term interactions between aboveground and belowground biota.  
  Address [Barantal, S; Roy, J; Fromin, N; Hattenschwiler, S] CEFE CNRS, UMR 5175, F-34293 Montpellier 5, France, Email: sandra.barantal@cefe.cnrs.fr  
  Corporate Author Thesis  
  Publisher Springer Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0029-8549 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000293914000024 Approved no  
  Call Number EcoFoG @ webmaster @ Serial 336  
Permanent link to this record
 

 
Author Houel, E.; Nardella, F.; Jullian, V.; Valentin, A.; Vonthron-Sénécheau, C.; Villa, P.; Obrecht, A.; Kaiser, M.; Bourreau, E.; Odonne, G.; Fleury, M.; Bourdy, G.; Eparvier, V.; Deharo, E.; Stien, D. url  openurl
  Title Wayanin and guaijaverin, two active metabolites found in a Psidium acutangulum Mart. ex DC (syn. P. persoonii McVaugh) (Myrtaceae) antimalarial decoction from the Wayana Amerindians Type Journal Article
  Year 2016 Publication Journal of Ethnopharmacology Abbreviated Journal Journal of Ethnopharmacology  
  Volume 187 Issue Pages (down) 241-248  
  Keywords Antimalarial; Cytokines; French guiana; Glycosylated flavonols; Psidium acutangulum; Traditional remedy  
  Abstract Ethnopharmacological relevance Psidium acutangulum Mart. ex DC is a small tree used by the Wayana Amerindians from the Upper-Maroni in French Guiana for the treatment of malaria. Aim of the study In a previous study, we highlighted the in vitro antiplasmodial, antioxidant and anti-inflammatory potential of the traditional decoction of P. acutangulum aerial parts. Our goal was then to investigate on the origin of the biological activity of the traditional remedy, and eventually characterize active constituents. Materials and methods Liquid-liquid extractions were performed on the decoction, and the antiplasmodial activity evaluated against chloroquine-resistant FcB1 ([3H]-hypoxanthine bioassay) and 7G8 (pLDH bioassay) P. falciparum strains, and on a chloroquine sensitive NF54 ([3H]-hypoxanthine bioassay) P. falciparum strain. The ethyl acetate fraction (D) was active and underwent bioguided fractionation. All the isolated compounds were tested on P. falciparum FcB1 strain. In vitro anti-inflammatory activity (IL-1β, IL-6, IL-8, TNFα) of the ethyl acetate fraction and of an anti-Plasmodium active compound, was concurrently assessed on LPS-stimulated human PBMC and NO secretion inhibition was measured on LPS stimulated RAW murine macrophages. Cytotoxicity of the fractions and pure compounds was measured on VERO cells, L6 mammalian cells, PBMCs, and RAW cells. Results Fractionation of the ethyl acetate soluble fraction (IC50 ranging from 3.4 to <1 μg/mL depending on the parasite strain) led to the isolation of six pure compounds: catechin and five glycosylated quercetin derivatives. These compounds have never been isolated from this plant species. Two of these compounds (wayanin and guaijaverin) were found to be moderately active against P. falciparum FcB1 in vitro (IC50 5.5 and 6.9 μM respectively). We proposed the name wayanin during public meetings organized in June 2015 in the Upper-Maroni villages, in homage to the medicinal knowledge of the Wayana population. At 50 μg/mL, the ethyl acetate fraction (D) significantly inhibited IL-1β secretion (-46%) and NO production (-21%), as previously observed for the decoction. The effects of D and guiajaverin (4) on the secretion of other cytokines or NO production were not significant. Conclusions The confirmed antiplasmodial activity of the ethyl acetate soluble fraction of the decoction and of the isolated compounds support the previous results obtained on the P. acutangulum decoction. The antiplasmodial activity might be due to a mixture of moderately active non-toxic flavonoids. The anti-inflammatory activities were less marked for ethyl acetate fraction (D) than for the decoction. © 2016 Elsevier Ireland Ltd. All rights reserved.  
  Address Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire de Biodiversité et Biotechnologies Microbiennes (LBBM), Observatoire Océanologique, Banyuls/Mer, France  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Export Date: 20 May 2016 Approved no  
  Call Number EcoFoG @ webmaster @ Serial 679  
Permanent link to this record
 

 
Author Leroy, C.; Carrias, J.-F.; Céréghino, R.; Corbara, B. url  doi
openurl 
  Title The contribution of microorganisms and metazoans to mineral nutrition in bromeliads Type Journal Article
  Year 2016 Publication Journal of Plant Ecology Abbreviated Journal Journal of Plant Ecology  
  Volume 9 Issue 3 Pages (down) 241-255  
  Keywords digestive mutualism; insect-assisted nutrients; leaf δ15N; multiple N sources; myrmecotrophy  
  Abstract Aims One critical challenge for plants is to maintain an adequate nutrient supply under fluctuating environmental conditions. This is particularly true for epiphytic species that have limited or no access to the pedosphere and often live in harsh climates. Bromeliads have evolved key innovations such as epiphytism, water-absorbing leaf trichomes, tank habit and Crassulacean acid metabolism (CAM) photosynthesis that enable them to survive under various environmental conditions. Bromeliads encompass diverse ecological types that live on different substrates (they can be terrestrial, epilithic or epiphytic) and vary in their ability to retain water (they can be tank-forming or tankless) and photosynthetic pathway (i.e. C3 or CAM). In this review, we outline the nutritional modes and specializations that enable bromeliads to thrive in a wide range of nutrient-poor (mostly nitrogen-depleted) environments. Important Findings Bromeliads have evolved a great diversity of morphologies and functional adaptations leading to the existence of numerous nutritional modes. Focusing on species that have absorptive foliar trichomes, we review evidence that bromeliads have evolved multi-faceted nutritional strategies to respond to fluctuations in the supply of natural nitrogen (N). These plants have developed mutualistic associations with many different and functionally diverse terrestrial and aquatic microorganisms and metazoans that contribute substantially to their mineral nutrition and, thus, their fitness and survival. Bacterial and fungal microbiota-assisted N provisioning, protocarnivory, digestive mutualisms and myrmecotrophic pathways are the main strategies used by bromeliads to acquire nitrogen. The combination of different nutritional pathways in bromeliads represents an important adaptation enabling them to exploit nutrient-poor habitats. Nonetheless, as has been shown for several other vascular plants, multiple partners are involved in nutrient acquisition indicating that there have been convergent adaptations to nutrient scarcity. Finally, we point out some gaps in the current knowledge of bromeliad nutrition that offer fascinating research opportunities. © The Author 2015. Published by Oxford University Press on behalf of the Institute of Botany, Chinese Academy of Sciences and the Botanical Society of China.  
  Address CNRS, EcoLab, 118 Route de Narbonne, Toulouse, France  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Export Date: 28 June 2016 Approved no  
  Call Number EcoFoG @ webmaster @ Serial 683  
Permanent link to this record
 

 
Author Fayad, I.; Baghdadi, N.; Bailly, J.-S.; Barbier, N.; Gond, V.; Herault, B.; El Hajj, M.; Fabre, F.; Perrin, J. pdf  url
doi  openurl
  Title Regional scale rain-forest height mapping using regression-kriging of spaceborne and airborne LiDAR data: Application on French Guiana Type Journal Article
  Year 2016 Publication Remote Sensing Abbreviated Journal Remote Sensing  
  Volume 8 Issue 3 Pages (down) 240  
  Keywords Airborne LiDAR; Canopy height mapping; Forests; French Guiana; ICESat GLAS  
  Abstract LiDAR data has been successfully used to estimate forest parameters such as canopy heights and biomass. Major limitation of LiDAR systems (airborne and spaceborne) arises from their limited spatial coverage. In this study, we present a technique for canopy height mapping using airborne and spaceborne LiDAR data (from the Geoscience Laser Altimeter System (GLAS)). First, canopy heights extracted from both airborne and spaceborne LiDAR were extrapolated from available environmental data. The estimated canopy height maps using Random Forest (RF) regression from airborne or GLAS calibration datasets showed similar precisions (~6 m). To improve the precision of canopy height estimates, regression-kriging was used. Results indicated an improvement in terms of root mean square error (RMSE, from 6.5 to 4.2 m) using the GLAS dataset, and from 5.8 to 1.8 m using the airborne LiDAR dataset. Finally, in order to investigate the impact of the spatial sampling of future LiDAR missions on canopy height estimates precision, six subsets were derived from the initial airborne LiDAR dataset. Results indicated that using the regression-kriging approach a precision of 1.8 m on the canopy height map was achievable with a flight line spacing of 5 km. This precision decreased to 4.8 m for flight line spacing of 50 km. © 2016 by the authors.  
  Address BRGM, 3 Avenue Claude Guillemin, Orléans, France  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Export Date: 22 April 2016 Approved no  
  Call Number EcoFoG @ webmaster @ Serial 675  
Permanent link to this record
 

 
Author Grangier, J.; Orivel, J.; Negrini, M.; Dejean, A. openurl 
  Title Low intraspecific aggressiveness in two obligate plant-ant species Type Journal Article
  Year 2008 Publication Insectes Sociaux Abbreviated Journal Insect. Soc.  
  Volume 55 Issue 3 Pages (down) 238-240  
  Keywords aggressiveness; Allomerus; myrmecophytes; plant-ants; recognition ability  
  Abstract Little is known about the aggressiveness of plant-ants typically living in isolated trees nor about how that aggressiveness varies based on this isolation. Here, we examine intra- and interspecific aggressiveness between workers of two Allomerus species associated with two different myrmecophytes. In both cases, the level of intraspecific aggressiveness is very low whatever the distance separating the tested nests, while interspecific conflicts are always violent. Similar patterns of aggressiveness have been reported in various ant species, but the strictly arboreal life of Allomerus ants associated with the isolation of their adult colonies highlight different ecological conditions that might explain the lack of aggressiveness between conspecifics.  
  Address [Grangier, J.; Orivel, J.; Negrini, M.; Dejean, A.] Univ Toulouse 3, CNRS, UMR 5174, Lab Evolut & Diversite Biol, F-31062 Toulouse 9, France, Email: grangier@cict.fr  
  Corporate Author Thesis  
  Publisher BIRKHAUSER VERLAG AG Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0020-1812 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000258959300004 Approved no  
  Call Number EcoFoG @ eric.marcon @ Serial 208  
Permanent link to this record
 

 
Author Picard, N.; Gourlet-Fleury, S.; Sist, P. openurl 
  Title Using process-dependent groups of species to model the dynamics of a tropical rainforest Type Journal Article
  Year 2003 Publication Modelling Forest Systems Abbreviated Journal  
  Volume Issue Pages (down) 237-248  
  Keywords  
  Abstract The high tree species diversity in tropical forests is difficult to take into account in models. The usual solution consists of defining groups of species and then adjusting a set of parameters for each group. In this study, we address this issue by allowing a species to move from one species group to another, depending on the biological process that is concerned. We developed this approach with a matrix model of forest dynamics, for a tropical rainforest in French Guiana, at Paracou, focusing on the methodological aspects. The forest dynamics is split into three components: recruitment, growth and mortality. We then built five recruitment groups, five growth groups and five mortality groups. One species is characterized by a combination of the three groups, thus yielding in total 5 X 5 X 5 = 125 possibilities, out of which 43 are actually observed. The resulting matrix model provides a better view of the floristic composition of the forest, and does not have more parameters than it would have with five global species groups. However, its predictions are no more precise than those of the matrix model based on five global groups.  
  Address Cirad Foret, Montpellier, France  
  Corporate Author Thesis  
  Publisher CABI PUBLISHING Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000231866400021 Approved no  
  Call Number EcoFoG @ eric.marcon @ Serial 249  
Permanent link to this record
 

 
Author Charles-Dominique, P.; Chave, J.; Dubois, M.A.; De Granville, J.J.; Riera, B.; Vezzoli, C. openurl 
  Title Colonization front of the understorey palm Astrocaryum sciophilum in a pristine rain forest of French Guiana Type Journal Article
  Year 2003 Publication Global Ecology and Biogeography Abbreviated Journal Glob. Ecol. Biogeogr.  
  Volume 12 Issue 3 Pages (down) 237-248  
  Keywords Astrocaryum sciophilum; French Guiana; neotropical palaeoecology; palm ecology; population edge; refuges; scatter-hoarding; seed dispersal; spatial pattern  
  Abstract Aims Astrocaryum sciophilum (Miq.) Pulle (Arecaceae) is an understorey palm, endemic to north-eastern South America with a patchy distribution. We tested the hypothesis that the spatial distribution of this palm species is not in equilibrium but is slowly colonizing the forest understorey. Location Inventories and seed dispersal studies were conducted in the undisturbed tropical forest close to the Nouragues research station, French Guiana. Additional data were collected in the entire territory of French Guiana. Methods We studied the demography of A. sciophilum on a 20-ha plot located at the edge of its distribution. The age of the palms was estimated by postulating an exponentially decreasing abundance by age class. Direct seed dispersal experiments were also conducted, to estimate dispersal parameters. The seeds of A. sciophilum were dispersed only by rodents. This information was used to parameterize a forest growth simulator, to study the spatial spread of this species. Results Within the sampling plot, the density of A. sciophilum dropped sharply from about 500 individuals per hectare to zero. The maturation age was estimated to be 170+/-70 years, and over 55 years with 95% confidence. Seed-dispersal experiments yielded an average seed dispersal distance of 11 m and a maximum estimated dispersal distance of 125 m across a generational span of 55 years to maturity. Therefore, the maximal estimated colonization speed is 2.3 m/y. Conclusions Empirical results and numerical simulations suggest that the boundary of the A. sciophilum population is a colonization front, and that the range of this species is slowly expanding. The implications of this result in respect of palaeoenvironmental changes in this region are discussed.  
  Address Natl Museum Nat Hist, Lab Ecol Gen, F-91800 Brunoy, France  
  Corporate Author Thesis  
  Publisher BLACKWELL PUBLISHING LTD Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0960-7447 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000182184100006 Approved no  
  Call Number EcoFoG @ eric.marcon @ Serial 273  
Permanent link to this record
Select All    Deselect All
 |   | 
Details
   print

Save Citations:
Export Records: