Du paysage à la population : impacts des changements d’usages et de la restauration face à la colonisation d’une espèce envahissante (Rubus ulmifolius Schott.) dans un écosystème sub-steppique méditerranéen

Studying an ecological phenomenon require to consider it in its entirety in order to apprehend all the causes and consequences. In the Plain of La Crau, a sub-steppic ecosystem in southeastern France, habitat fragmentation, loss of biodiversity and land-uses changes have fostered the encroachment by a species of brambles Rubus ulmifolius Schott of the original steppic patches. Using a multiscale analysis, the aims of the thesis are to highlight the main drivers, to assess the consequences on the plant community and to test restoration techniques by evaluating their effects on plant community and on bramble population. The presence of high proportions of irrigated habitats and formely fallows around invaded plots correspond to the largest cover rates of brambles. At community scale, water infiltrations have also a great impact on the steppe plant community by favoring the dynamic of an herbaceous competitor species: Brachypodium phoenicoïdes (L.) Roem. & Schult. Among the different disturbance regimes tested (scrub-clearing and / or grazing), crossed with the presence or the absence of sol draining, none could restore in the short-term (3 years), the integrity of the steppe reference. A significant increase in species richness and diversity was only measured for drained, scrub-cleared and annually grazed plots. At bramble population scale, the effects of the different treatments change depending on the year, the season and the time of the day. However, disturbance regimes (clearing and / or grazing) have more impact on eco-physiological and morphological traits of the bramble than the water resources limitation. Our results highlight the difficulty controlling short-term dynamics of an invasive species. They question the objectives of conservation and / or restoration of plots which can then be considered as degraded ecosystems or as "novel ecosystems" whose potential patrimonial values are still unknown.Etudier un phénomène écologique requiert de le considérer dans sa globalité afin d’appréhender l’ensemble de ses causes et ses conséquences. Dans la plaine de la Crau, écosystème pseudo-steppique du sud est de la France, la fragmentation des habitats, la perte de biodiversité et les changements d’usage ont favorisé l’envahissement de fragments relictuels de steppe par Rubus ulmifolius Schott. Par une approche multiscalaire, les objectifs de cette thèse sont de mettre en évidence les facteurs responsables de cet envahissement, d’appréhender ses conséquences sur la communauté végétale et de tester d’éventuelles techniques de restauration écologique en évaluant leurs effets à l’échelle de la communauté et de la population de ronces. La présence de fortes proportions de zones irriguées et de parcelles anciennement cultivées dans la matrice paysagère proche des zones envahies correspond à des taux de recouvrements parcellaires en ronciers plus élevés. A l’échelle de la communauté végétale, les infiltrations hydriques ont également des effets importants sur la végétation steppique en permettant le développement d’une espèce herbacée compétitrice : Brachypodium phoenicoïdes (L.) Roem. & Schult. Aucun des différents régimes de perturbation (débroussaillage et/ou pâturage) testés, croisés au drainage ou non du sol ne permet de restaurer à court terme (trois années) l’intégrité de la steppe de référence. Seule une augmentation significative de la richesse et de la diversité spécifique est mesurée dans le cas d’un débroussaillage et d’un pâturage annuel des placettes. A l’échelle des ronces, les effets des différents traitements varient selon l’année, la saison ou la période de la journée considérée. Les régimes de perturbation (débroussaillage et/ou pâturage) ont cependant plus d'influence sur les traits éco-physiologiques et morphologiques de la ronce que la limitation des ressources en eau. Nos résultats soulignent ainsi la difficulté de contrôler à court terme la dynamique d’une espèce envahissante. Ils ouvrent également le débat sur les objectifs de conservation et/ou de restauration des parcelles qui peuvent alors être considérées comme des écosystèmes dégradés ou comme de « nouveaux écosystèmes » dont les potentiels patrimoniaux sont encore inconnus

From landscape to population : impacts of land-use changes and restoration in regards to the colonization of an encroaching species (Rubus ulmifolius Schott.) in a Mediterranean sub-steppic ecosystem

Etudier un phénomène écologique requiert de le considérer dans sa globalité afin d’appréhender l’ensemble de ses causes et ses conséquences. Dans la plaine de la Crau, écosystème pseudo-steppique du sud est de la France, la fragmentation des habitats, la perte de biodiversité et les changements d’usage ont favorisé l’envahissement de fragments relictuels de steppe par Rubus ulmifolius Schott. Par une approche multiscalaire, les objectifs de cette thèse sont de mettre en évidence les facteurs responsables de cet envahissement, d’appréhender ses conséquences sur la communauté végétale et de tester d’éventuelles techniques de restauration écologique en évaluant leurs effets à l’échelle de la communauté et de la population de ronces. La présence de fortes proportions de zones irriguées et de parcelles anciennement cultivées dans la matrice paysagère proche des zones envahies correspond à des taux de recouvrements parcellaires en ronciers plus élevés. A l’échelle de la communauté végétale, les infiltrations hydriques ont également des effets importants sur la végétation steppique en permettant le développement d’une espèce herbacée compétitrice : Brachypodium phoenicoïdes (L.) Roem. & Schult. Aucun des différents régimes de perturbation (débroussaillage et/ou pâturage) testés, croisés au drainage ou non du sol ne permet de restaurer à court terme (trois années) l’intégrité de la steppe de référence. Seule une augmentation significative de la richesse et de la diversité spécifique est mesurée dans le cas d’un débroussaillage et d’un pâturage annuel des placettes. A l’échelle des ronces, les effets des différents traitements varient selon l’année, la saison ou la période de la journée considérée. Les régimes de perturbation (débroussaillage et/ou pâturage) ont cependant plus d'influence sur les traits éco-physiologiques et morphologiques de la ronce que la limitation des ressources en eau. Nos résultats soulignent ainsi la difficulté de contrôler à court terme la dynamique d’une espèce envahissante. Ils ouvrent également le débat sur les objectifs de conservation et/ou de restauration des parcelles qui peuvent alors être considérées comme des écosystèmes dégradés ou comme de « nouveaux écosystèmes » dont les potentiels patrimoniaux sont encore inconnus.Studying an ecological phenomenon require to consider it in its entirety in order to apprehend all the causes and consequences. In the Plain of La Crau, a sub-steppic ecosystem in southeastern France, habitat fragmentation, loss of biodiversity and land-uses changes have fostered the encroachment by a species of brambles Rubus ulmifolius Schott of the original steppic patches. Using a multiscale analysis, the aims of the thesis are to highlight the main drivers, to assess the consequences on the plant community and to test restoration techniques by evaluating their effects on plant community and on bramble population. The presence of high proportions of irrigated habitats and formely fallows around invaded plots correspond to the largest cover rates of brambles. At community scale, water infiltrations have also a great impact on the steppe plant community by favoring the dynamic of an herbaceous competitor species: Brachypodium phoenicoïdes (L.) Roem. & Schult. Among the different disturbance regimes tested (scrub-clearing and / or grazing), crossed with the presence or the absence of sol draining, none could restore in the short-term (3 years), the integrity of the steppe reference. A significant increase in species richness and diversity was only measured for drained, scrub-cleared and annually grazed plots. At bramble population scale, the effects of the different treatments change depending on the year, the season and the time of the day. However, disturbance regimes (clearing and / or grazing) have more impact on eco-physiological and morphological traits of the bramble than the water resources limitation. Our results highlight the difficulty controlling short-term dynamics of an invasive species. They question the objectives of conservation and / or restoration of plots which can then be considered as degraded ecosystems or as "novel ecosystems" whose potential patrimonial values are still unknown

Les déterminants de l'accès à la contraception de mineures en milieu rural du point de vue des professionnels de santé

Le taux d'IVG reste stable, en France, depuis une vingtaine d'année. Il a même tendance à augmenter chez les mineures, notamment dans l'Aude. Le parcours de soin concernant l'accès à la contraception est un chemin semé d'embuches, qui s'apparente même parfois à un vrai parcours du combattant. Si on y associe le manque d'informations et deconnaissances des jeunes filles et garçons, on comprend mieux l'évolution de ce taux. Nous avons étudié la vision des professionnels de santé de la Haute vallée del'Aude concernant l'accès à la contraception des mineures, en milieu rural, à l'aide d'une analyse qualitative d'entretiens semi-directifs. Les déterminants qui en ressortent sont les mêmes que ceux cités par les jeunes filles lors d'une précédente étude. L'accès doit pouvoir être gratuit, confidentiel et de proximité. La promotion de l'éducation à la sexualité et de l'information est importante, chez les jeunes comme chez les professionnels, chez qui la formation initiale et continue doit être renforcée. L'infirmière scolaire a un rôle clé dans cette éducation, et devrait pouvoir bénéficier des moyens adéquats pour mener à bien sa mission. Le pass contraception est identifié comme une bonne solution, notamment concernant la gratuité et l'anonymat. Mais ses restrictions l'empêchent d'obtenir l'unanimité et il doit être amélioré pour mieux correspondre à la réalité du terrain. Il faut multiplier les systèmes et les propositions, pour correspond re au maximum de personnes. Le travail en réseau semble une bonne alternative, il est plébiscité par les professionnels qui y voient l'avantage de créer des liens entre eux et de structurer le parcours de soinsMONTPELLIER-BU Médecine UPM (341722108) / SudocMONTPELLIER-BU Médecine (341722104) / SudocSudocFranceF

Impacts of water stress removal and disturbance regimes on Mediterranean dry grasslands diversity and succession

International audienceOur goal was to disentangle the effects of stress removal and disturbance on plant communities of a Mediterranean rangeland, La Crau (southeastern France). We compared undisturbed reference steppe vegetation with vegetation impacted by changes in land use such as earlier phases of cultivation (dating back 20 years) and/or current water infiltrations (revealed by the presence of Brachypodium phoenicoides), since the establishment of adjacent hay meadows. We considered plots with and without brambles (Rubus ulmifolius), an indigenous shrub species that had colonized the area after the land-use changes. We monitored the composition and measured the taxonomic richness and richness of functional groups, evenness and similarities of plant communities. The species richness of the undisturbed community was significantly higher than that of all disturbed plant communities. Although cultivation led to the dominance of ruderal species, the removal of water stress had a stronger negative impact, enabling the establishment of herbaceous competitor species such as B. phoenicoides. The dominance of this species resulted in a significant decline in species richness and evenness after water stress removal. The presence of brambles correlating with former cultivation and/or current water infiltration did not have a significant impact on plant species richness in the vicinity of bramble bushes, although it significantly modified the composition of the adjacent herbaceous vegetation. Our study highlights again the low resilience of Mediterranean dry grasslands after disturbance. While both the disturbance and the water stress removal resulted in changes within the plant community, our findings reveal a stronger impact of the water stress removal. Water infiltration led to decreased plant species richness and evenness because the greater availability of water favored competitor species over the stress-tolerant xeric species. Therefore, for restoring the original steppe species richness, the priority will be to control water infiltrations, even before any scrub-clearing is undertaken to control bramble colonization

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International audienc

The pseudo-steppe of La Crau (South-Eastern France): origin, management and restoration of a Mediterranean rangeland.

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Analyse croisée pour l'évaluation de la qualité environnementale urbaine : une approche interdisciplinaire et participative

International audienceThe goal of this research is to assess environmental quality at the neighbourhood level through a multi-dimensional and multi-sensory approach that combines social and physical methodologies. For this purpose, an interdisciplinary protocol has been designed to simultaneously collect physical parameter measurements (related to microclimate and acoustics) and survey data on perceptions (involving residents and non-residents). The cross-referenced analysis of data collected at six contrasting places in a district in Toulouse (France) enabled us (i) to better understand and prioritise the factors that influence residents' assessment of the quality of their living environment and (ii) to understand to what extent the differentiation of the places by the inhabitants converges with the differentiation of these places based on acoustic and micrometeorological measurements. The statistical analysis based on individuals showed the importance of noise and air quality that rank just after the aesthetic dimension for all respondents. Nevertheless, the quality of maintenance and the feeling of security that the place inspires seem to be as crucial as these environmental criteria for the inhabitants. The analysis focused on the sites highlighted the consistency between the typology of places based on perceptions and that based on acoustic measurements, which confirms the high inhabitants' sensitivity to this environmental component

Analyse croisée pour l'évaluation de la qualité environnementale urbaine : une approche interdisciplinaire et participative

International audienceThe goal of this research is to assess environmental quality at the neighbourhood level through a multi-dimensional and multi-sensory approach that combines social and physical methodologies. For this purpose, an interdisciplinary protocol has been designed to simultaneously collect physical parameter measurements (related to microclimate and acoustics) and survey data on perceptions (involving residents and non-residents). The cross-referenced analysis of data collected at six contrasting places in a district in Toulouse (France) enabled us (i) to better understand and prioritise the factors that influence residents' assessment of the quality of their living environment and (ii) to understand to what extent the differentiation of the places by the inhabitants converges with the differentiation of these places based on acoustic and micrometeorological measurements. The statistical analysis based on individuals showed the importance of noise and air quality that rank just after the aesthetic dimension for all respondents. Nevertheless, the quality of maintenance and the feeling of security that the place inspires seem to be as crucial as these environmental criteria for the inhabitants. The analysis focused on the sites highlighted the consistency between the typology of places based on perceptions and that based on acoustic measurements, which confirms the high inhabitants' sensitivity to this environmental component

Model of the Regional Coupled Earth system (MORCE): Application to process and climate studies in vulnerable regions

International audienceThe vulnerability of human populations and natural systems and their ability to adapt to extreme events and climate change vary with geographic regions and populations. Regional climate models (RCM), composed by an atmospheric component coupled to a land surface scheme and driven over ocean areas by prescribed sea surface temperature, have been developed to produce fine scale regional climate change information useful for impact assessment and adaptation studies. Although RCM can be sufficient for many applications, the Earth system is composed of the physical, chemical, biological, and social components, processes, and interactions that together determine the state and dynamics of Earth, including its biota and human occupants. Developing regional Earth system models has thus two primary motivations: (1) with respect to climate science, to improve modeling capabilities and better understand coupled processes at regional scales and (2) to support stakeholders who aim to use climate information for regionally-specific impact assessment and adaptation planning. IPSL in collaboration with ENSTA-ParisTech, LOPB, and CERFACS developed the MORCE (Model of the Regional Coupled Earth system) platform for process and climate studies of the regional Earth system. The original aspects of the MORCE platform are (1) the integration of a large number of coupled compartments and processes (physical and biogeochemical processes in the ocean, atmosphere and continent), (2) the transferability of the numerical platform to different locations in the world, (3) the use of a non-hydrostatic model for the atmospheric module which allows an accurate representation of kilometric scale processes. The present article describes the MORCE platform, detailing its various modules and their coupling and illustrating its potential with results obtained in the Mediterranean region and over the Indian Ocean

Analyse croisée pour l'évaluation de la qualité environnementale urbaine : une approche interdisciplinaire et participative

International audienceThe goal of this research is to assess environmental quality at the neighbourhood level through a multi-dimensional and multi-sensory approach that combines social and physical methodologies. For this purpose, an interdisciplinary protocol has been designed to simultaneously collect physical parameter measurements (related to microclimate and acoustics) and survey data on perceptions (involving residents and non-residents). The cross-referenced analysis of data collected at six contrasting places in a district in Toulouse (France) enabled us (i) to better understand and prioritise the factors that influence residents' assessment of the quality of their living environment and (ii) to understand to what extent the differentiation of the places by the inhabitants converges with the differentiation of these places based on acoustic and micrometeorological measurements. The statistical analysis based on individuals showed the importance of noise and air quality that rank just after the aesthetic dimension for all respondents. Nevertheless, the quality of maintenance and the feeling of security that the place inspires seem to be as crucial as these environmental criteria for the inhabitants. The analysis focused on the sites highlighted the consistency between the typology of places based on perceptions and that based on acoustic measurements, which confirms the high inhabitants' sensitivity to this environmental component