Providing more informative projections of climate change impact on plant distribution in a mountain environment

Summary Due to their conic shape and the reduction of area with increasing elevation, mountain ecosystems were early identified as potentially very sensitive to global warming. Moreover, mountain systems may experience unprecedented rates of warming during the next century, two or three times higher than that records of the 20th century. In this context, species distribution models (SDM) have become important tools for rapid assessment of the impact of accelerated land use and climate change on the distribution plant species. In my study, I developed and tested new predictor variables for species distribution models (SDM), specific to current and future geographic projections of plant species in a mountain system, using the Western Swiss Alps as model region. Since meso- and micro-topography are relevant to explain geographic patterns of plant species in mountain environments, I assessed the effect of scale on predictor variables and geographic projections of SDM. I also developed a methodological framework of space-for-time evaluation to test the robustness of SDM when projected in a future changing climate. Finally, I used a cellular automaton to run dynamic simulations of plant migration under climate change in a mountain landscape, including realistic distance of seed dispersal. Results of future projections for the 21st century were also discussed in perspective of vegetation changes monitored during the 20th century. Overall, I showed in this study that, based on the most severe A1 climate change scenario and realistic dispersal simulations of plant dispersal, species extinctions in the Western Swiss Alps could affect nearly one third (28.5%) of the 284 species modeled by 2100. With the less severe 61 scenario, only 4.6% of species are predicted to become extinct. However, even with B1, 54% (153 species) may still loose more than 80% of their initial surface. Results of monitoring of past vegetation changes suggested that plant species can react quickly to the warmer conditions as far as competition is low However, in subalpine grasslands, competition of already present species is probably important and limit establishment of newly arrived species. Results from future simulations also showed that heavy extinctions of alpine plants may start already in 2040, but the latest in 2080. My study also highlighted the importance of fine scale and regional. assessments of climate change impact on mountain vegetation, using more direct predictor variables. Indeed, predictions at the continental scale may fail to predict local refugees or local extinctions, as well as loss of connectivity between local populations. On the other hand, migrations of low-elevation species to higher altitude may be difficult to predict at the local scale. Résumé La forme conique des montagnes ainsi que la diminution de surface dans les hautes altitudes sont reconnues pour exposer plus sensiblement les écosystèmes de montagne au réchauffement global. En outre, les systèmes de montagne seront sans doute soumis durant le 21ème siècle à un réchauffement deux à trois fois plus rapide que celui mesuré durant le 20ème siècle. Dans ce contexte, les modèles prédictifs de distribution géographique de la végétation se sont imposés comme des outils puissants pour de rapides évaluations de l'impact des changements climatiques et de la transformation du paysage par l'homme sur la végétation. Dans mon étude, j'ai développé de nouvelles variables prédictives pour les modèles de distribution, spécifiques à la projection géographique présente et future des plantes dans un système de montagne, en utilisant les Préalpes vaudoises comme zone d'échantillonnage. La méso- et la microtopographie étant particulièrement adaptées pour expliquer les patrons de distribution géographique des plantes dans un environnement montagneux, j'ai testé les effets d'échelle sur les variables prédictives et sur les projections des modèles de distribution. J'ai aussi développé un cadre méthodologique pour tester la robustesse potentielle des modèles lors de projections pour le futur. Finalement, j'ai utilisé un automate cellulaire pour simuler de manière dynamique la migration future des plantes dans le paysage et dans quatre scénarios de changement climatique pour le 21ème siècle. J'ai intégré dans ces simulations des mécanismes et des distances plus réalistes de dispersion de graines. J'ai pu montrer, avec les simulations les plus réalistes, que près du tiers des 284 espèces considérées (28.5%) pourraient être menacées d'extinction en 2100 dans le cas du plus sévère scénario de changement climatique A1. Pour le moins sévère des scénarios B1, seulement 4.6% des espèces sont menacées d'extinctions, mais 54% (153 espèces) risquent de perdre plus 80% de leur habitat initial. Les résultats de monitoring des changements de végétation dans le passé montrent que les plantes peuvent réagir rapidement au réchauffement climatique si la compétition est faible. Dans les prairies subalpines, les espèces déjà présentes limitent certainement l'arrivée de nouvelles espèces par effet de compétition. Les résultats de simulation pour le futur prédisent le début d'extinctions massives dans les Préalpes à partir de 2040, au plus tard en 2080. Mon travail démontre aussi l'importance d'études régionales à échelle fine pour évaluer l'impact des changements climatiques sur la végétation, en intégrant des variables plus directes. En effet, les études à échelle continentale ne tiennent pas compte des micro-refuges, des extinctions locales ni des pertes de connectivité entre populations locales. Malgré cela, la migration des plantes de basses altitudes reste difficile à prédire à l'échelle locale sans modélisation plus globale.

Elevation gradient of successful plant traits for colonizing alpine summits under climate change

Upward migration of plant species due to climate change has become evident in several European mountain ranges. It is still, however, unclear whether certain plant traits increase the probability that a species will colonize mountain summits or vanish, and whether these traits differ with elevation. Here, we used data from a repeat survey of the occurrence of plant species on 120 summits, ranging from 2449 to 3418 m asl, in south-eastern Switzerland to identify plant traits that increase the probability of colonization or extinction in the 20th century. Species numbers increased across all plant traits considered. With some traits, however, numbers increased proportionally more. The most successful colonizers seemed to prefer warmer temperatures and well-developed soils. They produced achene fruits and/or seeds with pappus appendages. Conversely, cushion plants and species with capsule fruits were less efficient as colonizers. Observed changes in traits along the elevation gradient mainly corresponded to the natural distribution of traits. Extinctions did not seem to be clearly related to any trait. Our study showed that plant traits varied along both temporal and elevational gradients. While seeds with pappus seemed to be advantageous for colonization, most of the trait changes also mirrored previous gradients of traits along elevation and hence illustrated the general upward migration of plant species. An understanding of the trait characteristics of colonizing species is crucial for predicting future changes in mountain vegetation under climate change.

The hemodynamics of septic shock: a historical perspective.

In the late 19th century, it was already known that severe infections could be associated with cardiovascular collapse, a fact essentially attributed to cardiac failure. A major experimental work in the rabbit, published by Romberg and Pässler in 1899, shifted attention to disturbed peripheral vascular tone as the mechanism of hypotension in these conditions. In the first half of the 20th century, great progresses were made in the pathophysiologic understanding of hemorrhagic and traumatic shocks, while researchers devoted relatively little attention to septic shock. Progress in the hemodynamic understanding of septic shock resumed with the advent of critical care units. The hyperdynamic state was recognized in the late fifties and early sixties. The present short review ends with landmark studies by Max Harry Weil, demonstrating the importance of venous pooling, and John H. Siegel, which introduced the concept of deficient peripheral utilization of oxygen, inspiring later work on the microvascular disturbances of septic shock.

Politique fédérale des agglomérations dans les domaines des transports et de l'urbanisation

La croissance de la population, de l'économie et des transports individuels motorisés, particulièrement depuis la seconde moitié du 20ème siècle, ont notamment comme corollaire le développement urbanistique hors des frontières de la ville-centre et la formation des agglomérations. Ces zones urbaines sont stratégiques puisqu'elles accueillent une part toujours plus importante de la population et représentent le moteur de l'économie nationale. Toutefois, le développement des agglomérations et de la mobilité individuelle motorisée ne va pas sans poser de nombreux problèmes, dont la résolution nécessite de les aborder à l'échelle de l'agglomération, en coordonnant les transports et l'urbanisation. Notre système politique fédéral se définit notamment par une répartition des compétences dans une multitude de domaines entre les trois niveaux institutionnels de la Confédération, des cantons et des communes. Cette réalité est particulièrement vraie en matière d'aménagement du territoire. Il est à noter que les plus petites unités institutionnelles (les communes) conservent encore aujourd'hui des prérogatives importantes dans ce domaine. Au début des années 2000, la Confédération a développé une politique publique en faveur de ces zones stratégiques. Au moyen du fonds d'infrastructure, la politique fédérale des agglomérations dans les domaines des transports et de l'urbanisation est une politique publique incitative. Le dépôt, par les agglomérations, d'un projet respectant un cahier des charges précis et proposant des mesures de coordination entre les transports et l'urbanisation, permet d'obtenir un cofinancement fédéral du transport d'agglomération. Parmi les projets d'agglomération de première génération présentés à la Confédération, certains ont obtenu le cofinancement, d'autres pas. Le dimensionnement trop généreux des surfaces à bâtir fut notamment un facteur d'échec du projet d'agglomération de Fribourg, alors que la capacité à développer l'urbanisation à l'intérieur de l'agglomération fut un facteur de succès du projet Lausanne-Morges. L'analyse des projets d'agglomération Riviera et Monthey-Aigle, qui sont des projets de deuxième génération, confrontée à des entretiens avec des urbanistes et des responsables politiques, permet d'identifier leurs faiblesses et leurs atouts. Le projet d'agglomération Riviera présente une complémentarité des territoires et un grand potentiel de développement, mais aussi un manque de cohésion des partenaires du projet. Quant au projet Monthey-Aigle, il existe une réelle volonté politique de trouver des solutions aux conflits, mais les possibilités de développer les transports publics sont faibles. Dans le cadre de l'examen fédéral de ces deux projets d'agglomération, les éléments précités pourraient être des facteurs d'échec ou de succès. La politique publique fédérale invite les agglomérations à penser le développement de leurs transports et de leur urbanisation à un niveau global. La prise de hauteur et la coordination politique que cela suppose sont à même d'améliorer le lieu de vie des trois-quarts de la population suisse et de préserver le moteur de l'économie nationale. The growth of population, economy and personal motorised transportation, most particularly since the second half of the 20th century, has, as a consequence, induced an expansion of urban areas outside the borders of cities and encouraged the formation of urban agglomerations. These urban zones are of strategic importance as they attract an increasingly large population and represent a real driver of the national economy. However, the development of these agglomerations and the motorised mobility of their inhabitants cause numerous problems which require solutions to be adopted at the level of the agglomeration involving the interconnection of transport and urbanisation. Our federal political system is characterised by a distribution of responsibilities in many domains among the three institutional levels, namely the Confederation, the cantons and the communes. This is particularly the case of territorial developments. It should be noted that the smallest institutional units, the communes, still hold today important responsibilities in this area. At the beginning of the years 2000, the Confederation has developed a public policy in favour of these strategic zones. Through the establishment of an infrastructure fund, the federal policy in favour of urban agglomerations in the areas of transport and urbanisation aims at providing incentives to agglomerations. The submission by the agglomeration of a project containing a clear description of tasks and measures to integrate transport and urbanisation can result in a cofinancing participation by the Confederation in this project. Among the projects of first generation which had been submitted to the Confederation, some have received the cofinancing, others have not. The too generous dimension of the building areas in the project submitted by the agglomeration of Fribourg was a factor of its failure, while the capacity to develop urbanisation within the agglomeration was a factor of success for the Lausanne-Morges project. The analysis of the projects of the agglomerations Riviera and Monthey-Aigle which are projects of the second generation, as well as the interviews of urbanists and concerned officials have allowed us to identify their strengths and weaknesses. The Riviera project provides a complementary approach and a high potential of territorial developments, but at the same time denotes a lack of cohesion among partners of the project. With respect to the project Monthey-Aigle, there is a real political willingness to resolve conflicts, but the potential for the development of public transports is small. In the consideration by the Confederation of these two projects, the factors mentioned above may bring success or failure. The federal public policy incites the agglomerations to conceive the development of their transportation and urbanisation plans at a global level. The elevation of interests and the political coordination that this requires can improve the place of living of ¾ of the Swiss population and preserve the engine of growth of the national economy.

European climate variations over the past half-millennium reconstructed from groundwater

Temperature reconstructions for recent centuries are the basis of estimations of the natural variability in the climate system before and during the onset of anthropogenic perturbation. Here we present, for the first time, an independent and physically based reconstruction of mean annual temperature over the past half millennium obtained from groundwater in France. The reconstructed noble gas temperature (NGT) record suggests cooler than present climate conditions throughout the 16th-19th centuries. Periods of warming occur in the 17th-18th and 20th century, while cooling is reconstructed in the 19th century. A noticeable coincidence with other temperature records is demonstrated. Deuterium excess varies in parallel with the NGT, and indicates variation in the seasonality of the aquifer recharge; whereas high excess air in groundwater indicates periods with high oscillations of the water table.

Flore alpine et réchauffement climatique: observation de trois sommets valaisans à travers le XXe siècle

Alpine flora and climate change: monitoring of three summits in Valais (Switzerland) during the 20th century Climate change might trigger an upward shift of the flora in the Swiss Alps, especially since these experienced higher change in average than observed on a global scale. Previous investigations in the canton des Grisons (Switzerland) and Austria have revealed an increase of floristic diversity on alpine summits since the beginning of the 20th century. Three summits in Valais were revisited in this study: the Gornergrat (first inventory in 1919), the Torrenthorn (about in 1885) and the Beaufort (about in 1920). Every summit was newly inventoried in 2003 in the framework of the PERMANENT.PLOT.CH project. All showed a strong increase in species richness. On the Gornergrat (3135 m), 16 species were not found anymore, but 35 new ones were observed. The number of species on this exceptionally rich summit rose from 102 to 121. In comparison, the floristic richness increased from 24 to 63 species on the Torrenthorn (2924 m) and from 16 to 48 species on the Beaufort (3048 m). As in previous studies, this increase seems likely to be associated with climate change: the new species prefer, in average, higher temperature conditions than those previously prevailing on the summits. On the Gornergrat and Beaufort, our observations reveal a development of alpine meadows, whereas species typical of rocks and raw soils are predominantly colonising the Torrenthorn. This difference might be related to the important damage caused by wanderers on the vegetation of the Torrenthorn.

Impacts of Globalization Processes on the Swiss National Business Elite Community : A Diachronic Analysis of Swiss Large Corporations (1980-2010)

This paper investigates the impacts of globalization processes on the Swiss business elite community during the 1980-2010 period. Switzerland has been characterized in the 20th century by its extraordinary stability and by the strong cohesion of its elite community. To study recent changes, we focus on Switzerland's 110 largest firms' by adopting a diachronic perspective based on three elite cohorts (1980, 2000, and 2010). An analysis of interlocking directorates allows us to describe the decline of the Swiss corporate network. The second analysis focuses on top managers' profiles in terms of education, nationality as well as participation in national community networks that used to reinforce the cultural cohesion of the Swiss elite community, especially the militia army. Our results highlight a slow but profound transformation of top management profiles, characterized by a decline of traditional national elements of legitimacy and the emergence of new "global" elements. The diachronic and combined analysis brings into light the strong cultural changes experienced by the national business elite community.

Salvador Dalí: a spiritual gaze

There is a tendency to overlook the many fields that attracted Salvador Dalí, one of the most controversial figures of the 20th century. The Catalan artist was interested in painting, sculpture, engraving, opera, literature, advertising, dance, and even the theatre of life. Dalí was also a theoretician, constantly examining the processes of creation and knowledge: over the years he developed an imagery which, though changing, remained coherent, giving his body of work an unexpected unity.

Aux sources de l'orthopédie clinique : l'histoire revisitée de Jean-André Venel, "père de l'orthopédie" (fin XVIIIe-début XIXe siècle)

(ENGLISH VERSION BELOW) En 1780, le médecin Jean-André Venel fonde à Orbe, dans le canton de Vaud, le premier institut orthopédique connu dans le monde, proposant une version clinique d'un savoir-faire médical ancestral. A travers des sources qui réactualisent les travaux consacrés à Venel, cet article retrace les origines de son institution et de sa pensée médicale, dans un contexte de production et de diffusion d'un savoir particulier en termes de technique du corps et de médecine de l'enfant. Revisitant la figure légendaire - ou mythique ? - de ce que l'histoire de la médecine a retenu comme étant le « père de l'orthopédie », l'article s'interroge par la même occasion sur les conditions d'émergence d'une spécialité médicale au sortir de l'Ancien Régime, et de son impact dans les premières décennies du XIXe siècle. In 1780, the physician Jean-André Venel creates in Orbe (canton of Vaud) the first orthopedic institute of the world, offering a clinical version of an ancient medical savoir-faire. By using sources that enable us to update the scholarship on Venel, this article traces the origins of his institute and of his medical thought, in the context of the production and diffusion of a specialized knowledge on the body and on children. With this new perspective on the legendary, if not mythical, figure, whom the history of medicine has canonized as the "father of orthopedia", this article also examines the conditions of emergence of a medical specialization at the end of the Ancien Régime and its impact in the first decades of the nineteenth century.