Éditeur(s) : HAL CCSD Journal of West African Ornithology / Revue d'Ornithologie de l'Ouest Africain
Résumé : International audience
ISSN: 0331-3689

hal-01673690
https://hal.archives-ouvertes.fr/hal-01673690

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
In a period of agricultural decline in the uplands of Europe, agriculture is ceasing to provide the primary rationale for the organisation, utilisation and functioning of rural space. Policy reform, market trends and changes to the way citizens and consumers think about the countryside all suggest a need for thinking strategically about the future development of these areas. However, without a broad involvement of stakeholders, land use conflicts, and social and cultural conflicts in general, may increase. Involving stakeholders in upland areas can be facilitated by using scenario technique and by discussing alternative futures in local stakeholder panels. In this paper we present four scenarios of land-use change for the year 2030, and their assessments by stakeholder panels in Scotland, France, Norway, Switzerland, Slovakia and Greece. The aim of the paper is to explore the ways in which stakeholders in these locations advocate and assess these scenarios. We also explore how stakeholders in different countries weight the visual landscape impacts, the livelihood and biodiversity aspects of the scenarios in their assessment, and the reasons for their prioritising. The cross-country analysis shows that stakeholders across the study areas are united in their overall rejection of agricultural liberalisation, advocating a production-oriented, but multifunctional and environmentally-friendly agriculture that maintains landscapes and biodiversity.
ISSN: 0743-0167

halshs-01227527
https://halshs.archives-ouvertes.fr/halshs-01227527
DOI : 10.1016/j.jrurstud.2007.04.001

Éditeur(s) : HAL CCSD
Résumé :  
absent
9. Journées d'Ecologie Fonctionnelle
Biarritz, France

hal-01032071
https://hal.archives-ouvertes.fr/hal-01032071

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
ISSN: 0032-079X

hal-01092820
https://hal-agroparistech.archives-ouvertes.fr/hal-01092820
DOI : 10.1007/s11104-010-0333-2

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Few studies have investigated the influence of environmental conditions on the within-treevariation in Eucalyptus wood traits. The genotype and environment effects and their interactionsinfluence the wood properties. Their evaluations are crucial to estimate the genotype values andto select with efficiency. Thus, the aim of this study was to better understand the effect ofground slope and wind speed on the spatial variation of basic density (ρ), stiffness (MOE) andmicrofibril angle (MFA) of Eucalyptus wood. Wood discs cut along the trunk were sampledfrom 150 six-year-old Eucalyptus grandis x E. urophylla hybrids growing in 3 contrastinggrowing conditions influenced by ground slope and wind regime. Near Infrared (NIR)calibrations previously developed for ρ, MOE and MFA were used to predict in our discs. 2-Dplots presenting the spatial variation of predicted wood traits were compared. The higher theground slope, the greater the magnitude of radial variation in ρ, principally in the medium zoneof the trunk. The spatial variation of wood stiffness seems to be sensitive to two environmentalconditions. The MFA radial decreases were more pronounced where the wind speed was higher.At the base and top of the trees, however, there was no significant effect of growing conditionson the radial variation of the wood properties considered here.
ISSN: 0931-1890

hal-01451896
https://hal.archives-ouvertes.fr/hal-01451896
https://hal.archives-ouvertes.fr/hal-01451896/document
https://hal.archives-ouvertes.fr/hal-01451896/file/Art_Gril_al_Spatial_variation_wood_density_2016.pdf
DOI : 10.1007/s00468-015-1327-8

Éditeur(s) : HAL CCSD
Résumé : données, méthodes disponibles auprès de l'auteur
In tropical forest communities, interspecific competition and recruitment limitation by dispersal are two general mecanisms of tree species coexistence. Their role in regeneration remains poorly known, even though it is essential to understand them to better adress the gestion of exploited forests. In this work, environemental conditions and intraspecific relations were taken into account in the analysis of juvenile distribution. Fifteen species were retained according to a gradient of shade-tolerance and various seed dispersal modes. Statistical modelling of local density was used to link the success of installation with environnemental conditions and distances to adults simultaneously. Model prediction evidenced the gradient of shade-tolerance among studied species and revealed different installation curves related to dispersal modes.
Dans les communautés de forêt tropicale humide, la compétition interspécifique et la limitation du recrutement par la dispersion ont généralement invoquées pour expliquer la coexistence de nombreuses espèces d'arbres. Le rôle de ces mécanismes dans la régénération reste peu connu, bien que leur compréhension soit essentielle pour la gestion des forêts exploitées. Dans ce travail, les conditions du milieu et les relations intraspécifiques ont été prises en compte dans l'analyse des distributions de juvéniles. Quinze espèces non pionnières ont été sélectionnées selon un gradient de tolérance à l'ombre et des modes de dispersion variés. La modélisation statistique de la densité locale a permis de relier le succès d'installation des juvéniles aux conditions du milieu et aux distances aux arbres adultes simultanément. Les prédictions des
modèles confirment le gradient de tolérance parmi les espèces étudiées et révèlent des courbes d'installation différentes selon le mode de dispersion.
https://tel.archives-ouvertes.fr/tel-00297707

tel-00297707
https://tel.archives-ouvertes.fr/tel-00297707
https://tel.archives-ouvertes.fr/tel-00297707/document
https://tel.archives-ouvertes.fr/tel-00297707/file/PhD_regeneration_Olivier_Flores.pdf

Éditeur(s) : HAL CCSD Wiley
Résumé :  
Distinct ecosystem level carbon : nitrogen : phosphorus (C : N : P) stoichiometries in forest foliage have been suggested to reflect ecosystem-scale selection for physiological strategies in plant nutrient use. Here, this hypothesis was explored in a nutrient-poor lowland rainforest in French Guiana. * Variation in C, N and P concentrations was evaluated in leaf litter and foliage from neighbour trees of 45 different species, and the litter concentrations of major C fractions were also measured. * Litter C ranged from 45.3 to 52.4%, litter N varied threefold (0.68-2.01%), and litter P varied seven-fold (0.009-0.062%) among species. Compared with foliage, mean litter N and P concentrations decreased by 30% and 65%, respectively. Accordingly, the range in mass-based N : P shifted from 14 to 55 in foliage to 26 to 105 in litter. Resorption proficiencies indicated maximum P withdrawal in most species, but with a substantial increase in variation in litter P compared with foliage. * These data suggest that constrained ecosystem-level C : N : P ratios do not preclude the evolution of highly diversified strategies of nutrient use and conservation among tropical rainforest tree species. The resulting large variation in litter quality will influence stoichiometric constraints within the decomposer food web, with potentially far-ranging consequences on nutrient dynamics and plant-soil feedbacks.
ISSN: 0028-646X

hal-01032108
https://hal.archives-ouvertes.fr/hal-01032108
DOI : 10.1111/j.1469-8137.2008.02438.x

Éditeur(s) : HAL CCSD Wiley
Résumé :  
Drier periods from the late Pleistocene and early Holocene have been hypothesized to have caused the disappearance of various rainforest species over large geographical areas in South America and restricted the extant populations to mesic sites. Subsequent improvement in climatic conditions has been associated with recolonization. Changes in population size associated with these extinction-recolonization events should have affected genetic diversity within species. However, these historical hypotheses and their genetic consequences have rarely been tested in South America. Here, we examine the diversity of the chloroplast and nuclear genomes in a Neotropical rainforest tree species, Vouacapoua americana (Leguminosae, Caesalpinioideae) in French Guiana. The chloroplast diversity was analyzed using a polymerase chain reaction-restriction fragment length polymorphism method (six pairs of primers) in 29 populations distributed over most of French Guiana, and a subset of 17 populations was also analyzed at nine polymorphic microsatellite loci. To determine whether this species has experienced extinction-recolonization, we sampled populations in areas supposedly not or only slightly affected by climatic changes, where the populations would not have experienced frequent extinction, and in areas that appear to have been recently recolonized. In the putatively recolonized areas, we found patches of several thousands of hectares homogeneous for chloroplast variation that can be interpreted as the effect of recolonization processes from several geographical origins. In addition, we observed that, for both chloroplast and nuclear genomes, the populations in newly recolonized areas exhibited a significantly smaller allelic richness than others. Controlling for geographic distance, we also detected a significant correlation between chloroplast and nuclear population differentiation. This result indicates a cytonuclear disequilibrium that can be interpreted as a historical signal of a genetic divergence between fragmented populations. In conclusion, the spatial genetic structure of contemporary V. americana populations shows evidence that this species has experienced large extinction-recolonization events, which were possibly caused by past climatic change.
ISSN: 0014-3820

hal-01032194
https://hal.archives-ouvertes.fr/hal-01032194
DOI : 10.1111/j.0014-3820.2003.tb01517.x

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
OBJECTIVES:Blood rheology plays a key role in the pathophysiology of sickle cell anaemia (SS) and sickle cell haemoglobin C disease (SC), but its evolution over the lifespan is unknown.MATERIALS AND METHODS:Blood viscosity, red blood cell (RBC) deformability and aggregation, foetal haemoglobin (HbF) and haematocrit were measured in 114 healthy individuals (AA), 267 SS (161 children + 106 adults) and 138 SC (74 children + 64 adults) patients.RESULTS:Our results showed that 1) RBC deformability is at its maximal value during the early years of life in SS and SC populations, mainly because HbF level is also at its peak, 2) during childhood and adulthood, hydroxycarbamide treatment, HbF level and gender modulated RBC deformability in SS patients, independently of age, 3) blood viscosity is higher in older SS and SC patients compared to younger ones and 4) haematocrit decreases as SS patients age.CONCLUSION:The hemorheological changes detected in older patients could play a role in the progressive development of several chronic disorders in sickle cell disease, whose prevalence increases with age. Retarding these age-related haemorheological impairments, by using suitable drugs, may minimize the risks of vaso-occlusive events and chronic disorders.
ISSN: 1932-6203

Droits : http://creativecommons.org/licenses/by/
hal-01669747
https://hal.univ-antilles.fr/hal-01669747
DOI : 10.1371/journal.pone.0158182
PUBMED : 27355589
PUBMEDCENTRAL : PMC4927160

Éditeur(s) : HAL CCSD Wiley
Résumé : Decomposing litter provides critical nutrients for plants, particularly in nutrient-poor ecosystems such as tropical forests. We hypothesised that decomposing litter improves the performance of a variety of tropical tree seedlings, and that this litter effect varies depending on the species of litter present in litter mixtures. We addressed these hypotheses with a large pot experiment manipulating a range of different litter mixtures of contrasting quality and using seedlings of four tree species from the Amazonian forest of French Guiana. In contrast to our initial hypothesis, decomposing litter had either neutral or negative impacts on seedling growth, despite strongly different growth rates, biomass allocation patterns and leaf and root traits among tree species. Tree species varied in their responses to litter additions, which were further modified by species identity of the added litter. Our data show litter species-specific effects on growth, biomass allocation and leaf and root traits of tropical tree seedlings. These results suggest that a net nutrient release from decomposing litter does not necessarily improve tree seedling growth, even under nutrient-limiting conditions. In conclusion, litter layer composition may affect seedling establishment and recruitment success beyond litter-derived plant nutrient availability, which may contribute to tree species composition and dynamics in the studied tropical forest.
ISSN: 1435-8603

hal-01032421
https://hal.archives-ouvertes.fr/hal-01032421
DOI : 10.1111/j.1438-8677.2011.00534.x

Éditeur(s) : HAL CCSD Elsevier
Résumé :  
Tree species-rich tropical rainforests are characterized by a highly variable quality of leaf litter input to the soil at small spatial scales. This diverse plant litter is a major source of energy and nutrients for soil microorganisms, particularly in rainforests developed on old and nutrient-impoverished soils. Here we tested the hypothesis that the variability in leaf litter quality produced by a highly diverse tree community determines the spatial variability of the microbial respiration process in the underlying soil. We analyzed a total of 225 litter-soil pairs from an undisturbed Amazonian rainforest in French Guiana using a hierarchical sampling design. The microbial respiration process was assessed using substrateinduced respiration (SIR) and compared to a wide range of quality parameters of the associated litter layer (litter nutrients, carbon forms, stoichiometry, litter mass and pH). The results show that the variability of both litter quality and SIR rates was more important at large than at small scales. SIR rates varied between 1.1 and 4.0 mg g_1 h_1 and were significantly correlated with litter layer quality (up to 50% of the variability explained by the best mixed linear model). Total litter P content was the individual most important factor explaining the observed spatial variation in soil SIR, with higher rates associated to high litter P. SIR rates also correlated positively with total litter N content and with increasing proportions of labile C compounds. However, contrary to our expectation, SIR rates were not related to litter stoichiometry. These data suggest that in the studied Amazonian rainforest, tree canopy composition is an important driver of the microbial respiration process via leaf litter fall, resulting in potentially strong plant-soil feedbacks. .
ISSN: 0038-0717

hal-01032139
https://hal.archives-ouvertes.fr/hal-01032139
DOI : 10.1016/j.soilbio.2011.01.018

Éditeur(s) : HAL CCSD
Résumé : Correspondance : Dupraz@supagro.inra.fr
En conduite agroforestière, durant leurs premières années de croissance les arbres sont protégés par des abris individuels plastiques ventilés (disponibilité du C02, limitation de l'augmentation de temperature). Les arbres conduits en abri ont une croissance en biomasse totale comparable à celle des arbres sans abris (Dupraz, 1997b), mais présentent une croissance en hauteur plus importante,une croissance en diamètre inferieure (Bergez and Dupraz, 2000) et une biomasse racinaire plus faible de 17% (Dupraz, 1997a). Des études (Bergez and Dupraz, 2000 ; Dupraz and Bergez, 1999) ont conduit à éliminer la responsabilité des facteurs microclimatiques pour expliquer ces diffférences. Il restait un facteur explicatif : I'absence de sollicitation mécanique des arbres dans les abris. En effet, les sollicitations mécaniques telles que le vent induisent des mouvements des axes de plantes. Il a été démontré que les plantes ne perçoivent pas les forces auxquelles elles sont soumises mais leur état de déformation (Coutand and Moulia, 2000). Celle mécano-perception engendre des modifications de la croissance en dimension (Larson, 1954; Coutand et al., 2000) et de l'allocation de la biomasse des vegetaux (Niklas, 1998). Cette expérimentation avait donc pour but de voir si des arbres en abri soumis à des sollicitations mécaniques artificielles retrouvaient une croissance en dimensions et une répartition de la biomasse semblables à celle des arbres de plein vent. L'expérimentation a été conduite sur des merisiers d'un an et comportait 4 traitements : Abri, Abri+flexion artificielles, Sans Abri+vent, Sans abri+tuteurage. Les résultats ne montrent aucune différence de biomasse totale produite entre les 4 traitements. Par contre, les sollicitations mécaniques (naturelles ou artificielles) réduisent la croissance en hauteur (d'environ 60%), stimulent la croissance radiale d'environ 30% et induisent une allocation de la biomasse en faveur des racines. L'absence de sollicitations mécaniques est donc le facteur responsable des différences entre arbres en abri et arbres au vent.Quantitativement, les flexions artificielles n'étaient pas équivalentes à celles induites par le vent et n'ont pas mimé complètement les effets du vent. Reproduire les effets mécaniques du vent dans l'abri nécessite de parvenir à quantifier les variations d'état mécanique induites par le vent sur les axes des arbres. Ceci suppose donc d'abord de comprendre le couplage fluide-structure. Ce type de travail a été initié sur un couvet de luzerne, il explique les couplages vent-mouvements des tiges à la surface du couvert (Py, 2005). Ce type de travail pourrait servir de base à la prolongation de ce travail.
L'arbre isolé
Montpellier, France

hal-01032058
https://hal.archives-ouvertes.fr/hal-01032058

Éditeur(s) : HAL CCSD
Résumé : International audience
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, weconducted 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 totaltrait 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.
Ecology Letters

hal-01237101
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01237101
DOI : 10.1111/ele.12508
PUBMED : 26415616

Éditeur(s) : HAL CCSD Wiley
Résumé : Proper estimates of decomposition are essential for tropical forests, given their key role in the global carbon (C) cycle. However, the current paradigm for litter decomposition is insufficient to account for recent observations and may limit model predictions for highly diverse tropical ecosystems. In light of recent findings from a nutrient-poor Amazonian rainforest, we revisit the commonly held views that: litter traits are a mere legacy of live leaf traits; nitrogen (N) and lignin are the key litter traits controlling decomposition; and favourable climatic conditions result in rapid decomposition in tropical forests. Substantial interspecific variation in litter phosphorus (P) was found to be unrelated to variation in green leaves. Litter nutrients explained no variation in decomposition, which instead was controlled primarily by nonlignin litter C compounds at low concentrations with important soil fauna effects. Despite near-optimal climatic conditions, tropical litter decomposition proceeded more slowly than in a climatically less favourable temperate forest. We suggest that slow decomposition in the studied rainforest results from a syndrome of poor litter C quality beyond a simple lignin control, enforcing energy starvation of decomposers. We hypothesize that the litter trait syndrome in nutrient-poor tropical rainforests may have evolved to increase plant access to limiting nutrients via mycorrhizal associations.
ISSN: 0028-646X

hal-01032400
https://hal.archives-ouvertes.fr/hal-01032400
DOI : 10.1111/j.1469-8137.2010.03483.x

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : 1. This study focuses on the importance in hyperdiverse regions, such as the Amazonian forest, of accelerating and optimising the census of invertebrate communities.2. We carried out low-intensity sampling of tropical moth (Lepidoptera) assemblages in disturbed forest fragments in Brazil.3. We combined DNA barcoding and taxonomists' expertise to produce fast and accurate surveys of local diversity, including the recognition and census of undescribed and endemic species.4. Integrating expert knowledge of species distributions, we show that despite limited sampling effort, our approach revealed an unexpectedly high number of new and endemic species in severely threatened tropical forest fragments.5. These results highlight the risk of silent centinelan extinctions and emphasise the urgent need for accelerated invertebrate surveys in high-endemism and human-impacted tropical forests.
EISSN: 1752-458X

hal-01602363
https://hal.archives-ouvertes.fr/hal-01602363
DOI : 10.1111/icad.12187
PRODINRA : 389851

Éditeur(s) : HAL CCSD
Résumé : International audience
o abstract
ESA Annual Meeting
Milwaukee, United States

hal-01202970
http://hal.univ-reunion.fr/hal-01202970

Éditeur(s) : HAL CCSD
Résumé : More than 15% of Amazon forest has been converted to pastures these last decades. Some authors argued the world’s permanent pastures (30 % of total land) could potentially offset up to 4% of the global GHG emissions, having a carbon (C) storage potential equal to 0.5 Mg C.ha-1.yr-1(Schulze et al 2009). Accordingly, pastures are good candidates to increase soil uptake C in soil while ensuring a basic food production. Here we would like to assess the effects of tropical forest conversion to cattle pasture in the French Amazonia (French Guiana), by following the long-term dynamics of soil C stocks of permanent tropical pastures (Brachiaria humidicola) after deforestation from 1970. A soil inventory campaign was performed to analyse soil C and N stocks (to 1 m depth) along a pasture chronosequence of 6 months to 36 years old pastures and 4 native forest sites (total 24 sites). The annual C sequestration potential demonstrated by the chronosequence, was compared with eddy covariance flux measurements on 2 pastures and one native forest. Our study shows that old (≥ 24 years) tropical pastures resettle the recurrent C storage observed in native forest. These pastures stored between 1.8 ± 0.5 and 5.3 ± 2.1 tC ha-1 yr-1 compared with 2.6 ± 0.5 tC ha-1 yr-1 for the nearby native forest. Our finding show that old tropical pastures accumulate carbon in soil organic matter, particularly in the deep soil layers (0.2-1 m) and without loss of soil fertility. It suggests that such pastures can be exploited by farmers in the long term with appropriate practices (no fire and no overgrazing, but a mixture of grasses and legumes and a grazing rotation plan). Clearly, efforts to curb deforestation are a priority in order to preserve forest biodiversity and C stocks. But it seems now that, in a climate-smart agriculture way, the current challenge is to manage these deforested areas to maintain the productivity of agricultural ecosystems and in the same time their capacity to mitigate GES.
Building tomorrow’s research agenda and bridging the science-policy gap
Montpellier, France

hal-01204231
https://hal.archives-ouvertes.fr/hal-01204231
PRODINRA : 324147

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : Key message Molecular markers were used for paternity recovery in a maritime pine (Pinus pinasterAit.) polycross trial, facilitating forward selection. Different breeding strategies for seed orchard establishment were evaluated by comparing genetic gains and diversity. This work opens up new perspectives in maritime pine breeding.Context Polycross mating designs are widely used in forest tree breeding to evaluate parental breeding values for backward selection. Alternatively, polycross progeny trials may be used to select the best trees on the basis of individual breeding values and molecular pedigree analysis.Aims This study aimed to test such a forward selection strategy for the maritime pine breeding program.Methods In a maritime pine polycross trial, progeny with higher breeding values for growth and stem straightness was first preselected with or without relatedness constraints. After paternity recovery, the preselected trees were ranked on the basis of their breeding values, estimated from the recovered full pedigree. Finally, the best candidates were selected with three different strategies (forward, backward, mixed) and three levels of coancestry constraints to establish a virtual clonal seed orchard.Results Complete pedigrees were successfully recovered for most of the preselected trees. There was no major difference in expected genetic gains between the two preselection strategies which differed for relatedness constraints. Genetic gains were slightly higher for forward selection than for classical backward selection.Conclusion This seminal study opens up new perspectives for using forward selection within the French maritime pine breeding program.
ISSN: 1932-6203

hal-01601804
https://hal.archives-ouvertes.fr/hal-01601804
DOI : 10.1371/journal.pone.0049990
PRODINRA : 391860

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
BACKGROUND:Sickle cell anaemia (SCA) is a severe hereditary haemoglobinopathy characterised by haemorheological abnormalities, which play a role in the occurrence of several acute and chronic clinical complications. While βS -haplotypes and alpha-thalassaemia modulate SCA clinical severity, their effects on blood rheology have been incompletely described. The aim of this study was to test the effects of these genetic modifiers on the haemorheological properties and clinical complication of children with SCA.PROCEDURE:Steady-state haemorheological profile, biological parameters, βS -haplotypes, alpha-globin status, vaso-occlusive crisis (VOC) and acute chest syndrome frequencies were analysed in 128 children (aged 5 to 18 years) with SCA.RESULTS:Patients with alpha-thalassaemia showed increased red blood cell (RBC) deformability and aggregation compared to those without. Median VOC rate was higher in patients with homozygous alpha-thalassaemia compared to those with a normal alpha genotype. Conversely, the haemorheological profile and clinical complications were not influenced by the βS -haplotypes in our study.CONCLUSION:Our results demonstrate that alpha-thalassaemia is associated with higher risk for VOC events in children with SCA, which may be due in part to its effects on RBC deformability and aggregation.
ISSN: 1545-5009

hal-01668317
https://hal.univ-antilles.fr/hal-01668317
DOI : 10.1002/pbc.26455
PUBMED : 28097791

Éditeur(s) : HAL CCSD Hindawi Publishing Corporation
Résumé : International audience
ISSN: 1687-9708

hal-01555344
https://hal.univ-lorraine.fr/hal-01555344
DOI : 10.1155/2014/389409