Éditeur(s) : HAL CCSD
Résumé : In a perfect-deficit approach (Yi, 2012), the daily maximum carbon storage capacity (CPC) of a given ecosystem for each year defines the perfect annual CPC curve. Deficits are the differences in the daily observational data for a given year against a perfect curve. The area between this curve and instantaneous canopy photosynthetic rates represents the potential productivity. Using an 11-year (2004 – 2014) eddy covariance flux and meteorological data, this perfect-deficit approach was used to examine the relationship between potential productivity and droughts occurring in 2005 and 2010 in a tropical rainforest of French Guiana, South America. Surprisingly, CPC deficits were only reduced by 24% (2005) and 19% (2010) from their respective perfect CPCs, indicating a subtle effect of drought to ecosystem productivity. Highest precipitation occurred in 2010 but precipitation deficits dropped drastically during this year (71% reduction from its perfect value) which reflects a drought condition. However, its deficits showed no correlation annually and seasonally. Soil water content (SWC) appeared to be the single driver for CPC deficits during long dry periods but is weakly correlated (r = 0.30; P <0.01 and r = 0.31; P <0.01, in 2005 and 2010, respectively). These results indicate that soil water is not a major limiting factor for productivity of this ecosystem during drought periods. In contrast, global radiation (Rg) corresponds to the peak of CPC deficits in 2010, but only 19% had been reduced from its ideal value. Yet, highest gross primary production (GPP) of 4106±231 gCm−2yr−1 occurred this year (mean 3753±231 gCm−2yr−1). Therefore, smaller deficits in Rg coupled with sufficient water may have induced higher productivity in 2010. Nevertheless, weaker correlations between potential productivity and climatic drivers may imply that other controlling aspects such as biological constraints may also have an effect to the dynamics of potential productivity during drought events, hence, must also be considered.
AGU Fall Meeting 2015
San Francisco, United States

hal-01269439
https://hal.archives-ouvertes.fr/hal-01269439
PRODINRA : 338570

Éditeur(s) : HAL CCSD IOP Publishing
Résumé : Tropical forests of the Guiana Shield are the most affected by gold-mining in South America,experiencing an exponential increase in deforestation since the early 2000’s.Using yearly deforestation data encompassing Guyana, Suriname, French Guiana and theBrazilian State of Amapá, we demonstrated a strong relationship between deforestation due togold-mining and gold-prices at the regional scale. In order to assess additional drivers ofdeforestation due to gold-mining, we focused on the national scale and highlighted theheterogeneity of the response to gold-prices under different political contexts. Deforestation dueto gold-mining over the Guiana Shield occurs mainly in Guyana and Suriname. On the contrary,past and current repressive policies in Amapá and French Guiana likely contribute to thedecorrelation of deforestation and gold prices. In this work, wefinally present a case studyfocusing on French Guiana and Suriname, two neighbouring countries with very different levelsof law enforcement against illegal gold-mining. We developed a modelling framework to estimatepotential deforestation leakages from French Guiana to Suriname in the border areas. Based onour assumptions, we estimated a decrease in deforestation due to gold-mining of approx. 4 300hectares in French Guiana and an increase of approx. 12 100 hectares in Suriname in response tothe active military repression of illegal gold-mining launched in French Guiana.Gold-mining in the Guiana Shield provides challenging questions regarding REDDþimplementation. These questions are discussed at the end of this study and are important topolicy makers who need to provide sustainable alternative employment to local populations inorder to ensure the effectiveness of environmental policies.
ISSN: 1748-9326

hal-01512075
https://hal.archives-ouvertes.fr/hal-01512075
https://hal.archives-ouvertes.fr/hal-01512075/document
https://hal.archives-ouvertes.fr/hal-01512075/file/document%20%2828%29_%7B81107B08-30D1-44D2-877D-32F6DFAEF28A%7D.pdf
DOI : 10.1088/1748-9326/aa6082

Éditeur(s) : HAL CCSD
Résumé : International audience
ECS Trans.

hal-01239240
https://hal.archives-ouvertes.fr/hal-01239240

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
ISSN: 1874-3900

hal-01152699
https://hal.archives-ouvertes.fr/hal-01152699
DOI : 10.1016/j.phytol.2015.03.012

Éditeur(s) : HAL CCSD Masson
Résumé : National audience
Started in 2015 in Brazil, an outbreak linked to a little known arbovirus, Zika virus spread throughout Latin America. This virus, considered until recently as responsible of only mild symptoms, made mention of previously unsuspected complications, with severe neurological manifestations in adults and malformations of the central nervous system, including microcephaly, in newborns of mother infected during the pregnancy. While the continent is more accustomed to the succession of arbovirus epidemics, suspected complications and the many unknowns keys of the latter arriving raise many public health issues. French Guiana, a French territory located in the north-east of the continent, combines both European level of resources and climate and issues specific to the Amazon region and Latin America. We discuss here the issues for 2016 Zika virus epidemic in our region, many of them are generalizable to neighboring countries.
ISSN: 0037-9085

inserm-01422054
http://www.hal.inserm.fr/inserm-01422054
http://www.hal.inserm.fr/inserm-01422054/document
http://www.hal.inserm.fr/inserm-01422054/file/2016%2C%20Epelboin%20-%20%C3%89pid%C3%A9mie%20de%20virus%20Zika%20en%20Am%C3%A9rique%20latine%20-%20quels%20enjeux%20pour%20la%20Guyane%20%281%29.pdf
DOI : 10.1007/s13149-016-0490-5

Éditeur(s) : HAL CCSD
Résumé : International audience
26th Biennal meeting of the Caribbean academy of sciences
Deshaies, Guadeloupe

hal-01504621
https://hal-agroparistech.archives-ouvertes.fr/hal-01504621

Éditeur(s) : HAL CCSD Ecological Society of America
Résumé : Line transect surveys are widely used in neotropical rainforests to estimate the population abundance of medium- and large-sized vertebrates. The use of indices such as Encounter Rate has been criticized because the probability of animal detection may fluctuate due to the heterogeneity of environmental conditions among sites. In addition, the morphological and behavioral characteristics (biological traits) of species affect their detectability. In this study, we compared the extent to which environmental conditions and species' biological traits bias abundance estimates in terra firme rainforests in French Guiana. The selected environmental conditions included both physical conditions and forest structure covariates, while the selected biological traits included the morphological and behavioral characteristics of species. We used the distance sampling method to model the detection probability as an explicit function of environmental conditions and biological traits and implemented a model selection process to determine the relative importance of each group of covariates. Biological traits contributed to the variability of animal detectability more than environmental conditions, which had only a marginal effect. Detectability was best for large animals with uniform or disruptive markings that live in groups in the canopy top. Detectability was worst for small, solitary, terrestrial animals with mottled markings. In the terra firme rainforests which represent ~80% of the Amazonia and Guianas regions, our findings support the use of relative indices such as the encounter rate to compare population abundance between sites in species-specific studies. Even though terra firme rainforests may appear similar between regions of Amazonia and the Guianas, comparability must be ensured, especially in forests disturbed by human activity. The detection probability can be used as an indicator of species' vulnerability to hunting and, thus, to the risk of local extinction. Only a few biological trait covariates are required to correctly estimate the detectability of the majority of medium- and large-sized vertebrates. Thus, a biological trait model could be useful in predicting the detection probabilities of rare, uncommon or localized species for which few data are available to fit the detection function.
ISSN: 1051-0761

hal-01555267
https://hal.archives-ouvertes.fr/hal-01555267
DOI : 10.1002/eap.1549
PRODINRA : 396614
PUBMED : 28419598

Éditeur(s) : HAL CCSD Royal Society, The
Résumé : International audience
Many studies have focused on the impacts of climate change on biological assemblages, yet little is known about how climate interacts with other major anthropogenic influences on biodiversity, such as habitat disturbance. Using a unique global database of 1128 local ant assemblages , we examined whether climate mediates the effects of habitat disturbance on assemblage structure at a global scale. Species richness and evenness were associated positively with temperature, and negatively with disturbance. However, the interaction among temperature, precipitation and disturbance shaped species richness and evenness. The effect was manifested through a failure of species richness to increase substantially with temperature in transformed habitats at low precipitation. At low precipitation levels, evenness increased with temperature in undisturbed sites, peaked at medium temperatures in disturbed sites and remained low in transformed sites. In warmer climates with lower rainfall, the effects of increasing disturbance on species richness and evenness were akin to decreases in temperature of up to 98C. Anthropogenic disturbance and ongoing climate change may interact in complicated ways to shape the structure of assemblages, with hot, arid environments likely to be at greatest risk.
ISSN: 0962-8452

hal-01323255
https://hal.archives-ouvertes.fr/hal-01323255
DOI : 10.1098/rspb.2015.0418

Éditeur(s) : HAL CCSD Elsevier
Résumé : While around 20% of the Amazonian forest has been cleared for pastures and agriculture, one fourth of the remaining forest is dedicated to wood production [1] . Most of these production forests have been or will be selectively harvested for commercial timber, but recent studies show that even soon after logging, harvested stands retain much of their tree-biomass carbon and biodiversity [2,3] . Comparing species richness of various animal taxa among logged and unlogged forests across the tropics, Burivalova et al. [4] found that despite some variability among taxa, biodiversity loss was generally explained by logging intensity (the number of trees extracted). Here, we use a network of 79 permanent sample plots (376 ha total) located at 10 sites across the Amazon Basin [5] to assess the main drivers of time-to-recovery of post-logging tree carbon ( Table S1 ). Recovery time is of direct relevance to policies governing management practices (i.e., allowable volumes cut and cutting cycle lengths), and indirectly to forest-based climate change mitigation interventions.
ISSN: 0960-9822

hal-01536542
https://hal.archives-ouvertes.fr/hal-01536542
DOI : 10.1016/j.cub.2015.07.034
PRODINRA : 343217
PUBMED : 26394096

Éditeur(s) : HAL CCSD Royal Society, The
Résumé : There is broad consensus that the diversity of functional traits within species assemblages drives several ecological processes. It is also widely recognized that rare species are the first to become extinct following human-induced disturbances. Surprisingly, however, the functional importance of rare species is still poorly understood, particularly in tropical species-rich assemblages where the majority of species are rare, and the rate of species extinction can be high. Here, we investigated the consequences of local and regional extinctions on the functional structure of species assemblages. We used three extensive datasets (stream fish from the Brazilian Amazon, rainforest trees from French Guiana, and birds from the Australian Wet Tropics) and built an integrative measure of species rarity versus commonness, combining local abundance, geographical range, and habitat breadth. Using different scenarios of species loss, we found a disproportionate impact of rare species extinction for the three groups, with significant reductions in levels of functional richness, specialization, and originality of assemblages, which may severely undermine the integrity of ecological processes. The whole breadth of functional abilities within species assemblages, which is disproportionately supported by rare species, is certainly critical in maintaining ecosystems particularly under the ongoing rapid environmental transitions.
ISSN: 0962-8452

hal-01532639
https://hal.archives-ouvertes.fr/hal-01532639
DOI : 10.1098/rspb.2016.0084
PRODINRA : 384617

Éditeur(s) : HAL CCSD
Résumé : Xth world conference SEA 2016, Rome, 13-15 juin 2016
https://hal-agroparistech.archives-ouvertes.fr/hal-01504655

hal-01504655
https://hal-agroparistech.archives-ouvertes.fr/hal-01504655

Éditeur(s) : HAL CCSD
Résumé : For a decade, distance-based methods have been widely employed and constantly improved in the field of spatial economics. These methods are a very useful tool for accurately evaluating the spatial distribution of plants or retail stores, for example (Duranton and Overman, 2008). In this paper, we introduce a new distance-based statistical measure for evaluating the spatial concentration of economic activities. To our knowledge, the m function is the first relative density function to be proposed in the economics literature. This tool supplements the typology of distance-based methods recently drawn up by Marcon and Puech (2012). By considering several theoretical and empirical examples, we show the advantages and the limits of the m function for detecting spatial structures in economics.
https://hal.archives-ouvertes.fr/hal-01082178

hal-01082178
https://hal.archives-ouvertes.fr/hal-01082178
https://hal.archives-ouvertes.fr/hal-01082178v3/document
https://hal.archives-ouvertes.fr/hal-01082178/file/LANG-%20MARCON-PUECH%20-%20m%20-%20HAL%2001082178v3.pdf

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
INTRODUCTION:The frequency, the clinical characteristics, and the prognosis of dengue is highly variable. Dengue fever is associated with a range of neurological manifestations. The objective of the present study was to determine the incidence of neurological signs and their predictive factors using data from cases of dengue seen and followed in Cayenne Hospital during the Dengue 2 epidemic in 2013.METHODS:In 2013, a longitudinal study using data from all cases of dengue seen in Cayenne hospital was collected. Medical records used a standardized form to collect demographic information, clinical signs and biological results and the date at which they were present. The analysis used Cox proportional modeling to obtain adjusted Hazard ratios.RESULTS:A total of 1574 patients were included 221 of whom developed central nervous system signs. These signs were spontaneously resolutive. There were 9298person days of follow-up and the overall incidence rate for central nervous system signs was 2.37 per 100 person-days. The variables independently associated with central nervous system anomalies were headache, Adjusted Hazard ratio (AHR) = 1.9(95%CI = 1.4-2.6), bleeding AHR = 2 ((95%CI = 1.3-3.1), P = 0.001, abdominal pain AHR = 1.9 ((95%CI = 1.4-2.6), P<0.001, aches AHR = 2.1 ((95%CI = 1.5-2.9), P<0.001, and fatigue AHR = 1.5 ((95%CI = 1.3-1.7), P<0.001.DISCUSSION:Overall, the present study suggests that neurological signs of dengue are not exceptional even in patients without the most severe features of dengue. These manifestations were spontaneously resolutive. Here it was not possible to distinguish between encephalitis or encephalopathy. Further studies would require more in depth exploration of the patients.
ISSN: 1932-6203

inserm-01421218
http://www.hal.inserm.fr/inserm-01421218
http://www.hal.inserm.fr/inserm-01421218/document
http://www.hal.inserm.fr/inserm-01421218/file/2016%2C%20Djossou%20-%20Incidence%20and%20Predictive%20Factors%20of%20Central%20Nervous%20System%20Dysfunction%20in%20Patients%20Consulting.pdf
DOI : 10.1371/journal.pone.0150828.t003

Éditeur(s) : HAL CCSD
Résumé : National audience
La Guyane française, de par sa situation géographique et climatique équatoriale – entraînant uneimmense biodiversité – et le caractère multiculturel et multiethnique de sa population, est le siège d’unlarge panel de pathologies infectieuses et tropicales, dont certaines sont assez mal connues.La fièvre Q, la toxoplasmose, la cryptococcose ou l’infection à VIH sont communes aux pays tempérés,mais présentent ici de grandes spécificités, entraînant une prise en charge et un raisonnement médicalparfois différents. De nombreuses pathologies tropicales sont par ailleurs présentes sur un mode endémiqueet/ou épidémique : paludisme, leishmaniose, maladie de Chagas, histoplasmose, dengue, chikungunya, etc.Des personnes ayant séjourné en Guyane peuvent présenter des problèmes infectieux spécifiques deretour sur le continent européen, et ces pathologies doivent pouvoir être évoquées par l’infectiologue.
La Lettre de l'Infectiologue

inserm-01407150
http://www.hal.inserm.fr/inserm-01407150
http://www.hal.inserm.fr/inserm-01407150/document
http://www.hal.inserm.fr/inserm-01407150/file/2016%2C%20Epelboin%20-%20L%27infectiologie%20en%20Guyane%20synth%C3%A8se%20med%20trop.pdf

Éditeur(s) : HAL CCSD Presses Universitaires de France
Résumé : ISBN 2-13-056651-9
Les jeunes enfants sont confrontés dès leur plus jeune âge à un environnement sémiotique où l'image et l'icône sont très présents, par le biais de leurs jouets, de leurs livres d'images, des dessins animés, et d'écrits nombreux ... Grâce à cette iconicité très stéréotypée, ils acquièrent rapidement une culture du signe iconique, apportée par l'adulte sans que celui-ci ait nécessairement conscience du contenu ainsi transmis. Par ailleurs, l'environnement scriptural de l'adulte fait lui-même une part très large à l'icône en général et au pictogramme en particulier. On sait que le pictogramme est un signe qui, malgré son caractère iconique et son apparence simple, voire simpliste, est souvent difficile à interpréter correc­tement par les adultes et que les erreurs en ce domaine sont plus fréquentes qu'on ne le croit. Le recours aux savoirs du « lecteur », aux stéréotypes scriptovisuels qu'il connaît, à son expérience, est nécessaire pour l'interprétation mais en même temps source d'erreurs. En effet, la compréhension de ces signes, loin de relever d'un réalisme naïf permettant de voir la « chose » à travers son image, requiert une compétence sémiotique et le recours à des interprétants externes, qui sont à la fois du domaine du contexte (entour du signe), et de celui de l'intertexte polysémiotique constitué par une culture intériorisé. Or le rôle de ces interprétants externes est tel que le recours à d'autres interprétants que ceux que l'émetteur du signe avait en vue peut conduire à des interprétations nettement divergentes à la lecture. Dès lors, nous nous demandons comment ces signes sont perçus par les enfants et plus particulièrement par les enfants pré-lecteurs, comment ceux-ci parviennent, ou non, à les sémiotiser, à les décrypter, à les interpréter. Nous avons donc proposé à des enfants fréquentant l'école (maternelle ou élémentaire) une série de pictogrammes. Il s'agit, en leur demandant simplement ce qu'ils comprennent, d'interroger leurs connaissances en matière de signe iconique et la manière dont ils arrivent à les réinvestir pour cons­truire du sens. Par ce biais, nous nous interrogeons également sur la manière dont ces enfants perçoivent ces signes qui ne leur sont pas spécifiquement destinés (voire pas du tout dans le cas de la signalisation routière, des pictogrammes « de gare », ou des modes d'emploi ...) mais qu'ils perçoivent cependant. Nous tentons enfin par là d'explorer la lisibilité de notre environnement scriptural « à hau­teur d'enfant ».
Les âges de la vie : Sémiotique de la culture et du temps

hal-00330427
https://hal.archives-ouvertes.fr/hal-00330427

Éditeur(s) : HAL CCSD Ecological Society of America
Résumé : Herbivory is viewed as a major driver of plant evolution and the mostimportant energy pathway from plants to higher trophic levels. Therefore, understandingpatterns of herbivory on plants remains a key focus in evolution and ecology. Theevolutionary impacts of leaf herbivory include altering plant fitness, local adaptation, theevolution of defenses, and the diversification of plants as well as natural enemies. Leafherbivory also impacts ecological processes such as plant productivity, communitycomposition, and ecosystem nutrient cycling. Understanding the impact of herbivory onthese ecological and evolutionary processes requires species-specific, as opposed tocommunity-level, measures of herbivory. In addition, species-specific data enables the use ofmodern comparative methods to account for phylogenetic non-independence. Althoughhundreds of studies have measured natural rates of leaf consumption, we are unaware of anyaccessible compilation of these data. We created such a data set to provide the raw dataneeded to test general hypotheses relating to plant–herbivore interactions and to test theinfluence of biotic and abiotic factors on herbivory rates across large spatial scales. A largerepository will make this endeavor more efficient and robust. In total, we compiled 2641population-level measures for either annual or daily rates of leaf herbivory across 1145 speciesof vascular plants collected from 189 studies. All damage measures represent naturaloccurrences of herbivory that span numerous angiosperm, gymnosperm, and fern species. Toenable researchers to explore the causes of variation in herbivory and how these mightinteract, we added information about the study sites including: geolocation, climateclassification, habitat descriptions (e.g., seashore, grassland, forest, agricultural fields), andplant trait information concerning growth form and duration (e.g., annual vs. perennial). Wealso included extensive details of the methodology used to measure leaf damage, includingseasons and months of sampling, age of leaves, and the method used to estimate percentagearea missing. We anticipate that these data will make it possible to test important hypothesesin the plant–herbivore literature, including the plant apparency hypothesis, the latitudinalherbivorydefense hypothesis, the resource availability hypothesis, and the macroevolutionaryescalation of defense hypothesis.
ISSN: 0012-9658

hal-01601627
https://hal.archives-ouvertes.fr/hal-01601627
DOI : 10.1890/13-1741.1
PRODINRA : 397136
PUBMED : 24870043

Éditeur(s) : HAL CCSD springer Link
Résumé : International audience
Experimental Astronomy

hal-01094521
https://hal.archives-ouvertes.fr/hal-01094521
BIBCODE : 2014ExA...tmp...41R
DOI : 10.1007/s10686-014-9383-4
ARXIV : 1310.0696

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : Intraguild predation (IGP) is a type of biological interaction involving the killing and consuming of competing species that exploit similar and often limited resources. This phenomenon is widespread among a great variety of taxonomic groups and has already been reported for mosquito (Diptera: Culicidae) larvae. Moreover, the larvae of certain mosquito species of the tribe Sabethini have evolved modified mouthparts ending in rigid apical structures signaling their capacity to be effective intraguild predators. We assumed that IGP confers a selective advantage under severe competitive conditions by both providing an immediate energetic gain and reducing potential competition. Because potential competition is likely to increase with decreasing habitat size, we hypothesized that the proportion of species with modified mouthparts would increase in smaller aquatic habitats. We tested this hypothesis by examining the mosquito species naturally associated with phytotelmata of decreasing sizes in French Guiana. We show that the degree of specialization in mosquito-phytotelm associations is high, suggesting a long coevolutive process. Indeed, short-term interaction experiments confirmed that species with modified mouthparts are able to prey upon similarly-sized intraguild prey and are, thus, effective intraguild predators. In addition, these species are larger and associated with smaller phytotelmata than those with typical mouthparts. Moreover, below a certain threshold of phytotelm size, only species with modified mouthparts were present. These results show that IGP confers a selective advantage under severe competitive conditions and results from the coadaptation of mosquito species to their specific phytotelm habitat. The presence of functionally analogous structures in different mosquito genera also implies that IGP has emerged from convergent evolution in small phytotelmata.
ISSN: 0269-7653

hal-01603304
https://hal.archives-ouvertes.fr/hal-01603304
DOI : 10.1007/s10682-016-9862-3
PRODINRA : 405771

Éditeur(s) : HAL CCSD
Résumé : International audience
o abstract
Revue Des Maladies Respiratoires

hal-01647782
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01647782
DOI : 10.1016/j.rmr.2017.07.017
PUBMED : 28939155

Éditeur(s) : HAL CCSD University of California, Los Angeles
Résumé : International audience
entropart is a package for R designed to estimate diversity based on HCDT entropy or similarity-based entropy. It allows calculating species-neutral, phylogenetic and functional entropy and diversity, partitioning them and correcting them for estimation bias. © 2015, American Statistical Association.
ISSN: 1548-7660

hal-01502646
https://hal-agroparistech.archives-ouvertes.fr/hal-01502646
DOI : 10.18637/jss.v067.i08