L’Ascension, 2017, par Ludovic Bernard

« Ils·elles n’ont pas les codes ». Voilà des propos entendus mainte fois lors du premier déconfinement, autant par des professionnels de la montagne que des élus locaux. En juin 2020, la quantité inhabituelle de touristes nouvellement venus à la montagne avait créé un surprenant malaise : la fréquentation massive de personnes débarquant pour la première fois en montagne bousculait une certaine intériorisation de cette dernière comme un espace « réservé ». Sans nier la réalité d’incivilités, l..

Taxonomic revision of West-Alpine cushion plant species belonging to Androsace subsect. Aretia

International audienceHigh-altitude rockjasmines (genus Androsace) are a paramount example of evolutionary radiations in temperate mountains of the Northern Hemisphere. Yet, we show here that their taxonomy is incomplete and has been subject to many historical mistakes, probably due to the lack of exploration of mountains by the classical botanists who described these species. Here we wish to clarify the application of names with regard to four defined morphotypes, typical of high-elevation zones of the Western Alps, in order to set a definitive basis for morphological delimitation of a likely new species discovered in the Mont Blanc range (species not described in this work). To do so, we review the historical taxonomic treatments and positions, carefully reconsider types and species names for these morphotypes, and designate lectotypes and epitypes for each of them. In particular, we confirm the validity of names commonly used to refer to the taxa Androsace alpina, Androsace helvetica, and Androsace pubescens. We show that Androsace vandellii is an invalid name and that Androsace argentea should be used instead. Our work illustrates the utility of historical herbaria to clarify the taxonomy of complex groups of plants growing in inaccessible environments such as high-altitude regions

Synthèse botanique du Mont Aiguille (Réserve naturelle des Hauts Plateaux du Vercors). Compte-rendu de l'expédition des 5 et 6 juillet 2022 et analyse bibliographique

Synthèse et compte-rendu d'une mission scientifiqueIn the framework of a vegetation monitoring, a scientific ascent and exploration of Mont Aiguille was carried out in 2022. A critical review of the plant diversity of this site is proposed here, as well as a reference list of floristic species. Finally, two remarkable species of Mont Aiguille (Tulipa australis and Pinus mugho subsp. uncinata) are analyzed through a historical ecology approach.Dans le cadre d'un suivi de végétation, une ascension et exploration scientifique du Mont Aiguille ont été réalisées en 2022. Une relecture critique de la diversité végétale de ce site est ici proposée, ainsi qu'une liste de référence des espèces floristiques. Enfin, deux espèces remarquables du Mont Aiguille (Tulipa australis et Pinus mugho subsp. uncinata) sont analysée par une approche d'écologie historique

Les alpinistes et les limites terrestres du vivant : une contribution atypique à la connaissance scientifique

International audienceLa montagne et les nouvelles manières de faire connaissance Les alpinistes et les limites terrestres du vivant : une contribution atypique à la connaissance scientifiqu

Alpinists and the Terrestrial Limits of Living Beings: an Atypical Contribution to Scientific Knowledge

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Anthropocene trajectories of high alpine vegetation on Mont-Blanc nunataks

International audienceClimate warming causes dramatic glacier retreat and intense vegetation changes in alpine regions. High-elevation nunataks, that is bedrock islands protruding from glaciers with uppermost flowering plants, are no exception. Yet the consequences of climate change on nunatak vegetation remain relatively unexplored. Here, we report findings from a re-visit of historical plant surveys carried out on six nunataks situated between 2180 m a.s.l. and 3509 m a.s.l. amidst the glaciers of the Mont-Blanc range (France). We compared vegetation surveys conducted in 2020 to those made 150 years before, and performed remote sensing analyses to depict changes in vegetation productivity during recent decades. We report an increase in plant species richness for the lowest and least isolated nunataks, which contributed to a strong signal of vegetation greening over the last 35 years. This trend was due to the upward migration of competitive species, but also due to species colonization from neighboring high alpine areas into recently unglaciated microsites. We also highlight striking ecological trajectories that have been little discussed so far, such as stable vegetation composition in the highest and most isolated nunataks, an increase of plant species associated with non-permanent snow-cover and water run-off, an increase of graminoids at lower elevations, and of phanerophytes at higher elevations. We argue that high alpine vegetation changes are not driven by the sole upward migration of lowland competitive species, and that careful monitoring of ongoing ecological changes over broad elevation gradients is necessary to better understand the rapid transformation of high alpine landscapes

Observed long-term greening of alpine vegetation—a case study in the French Alps

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Méthodologie de suivi des espèces végétales rares mise en place par un réseau d’acteurs de la conservation

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Data from: Riders in the sky (islands): using a mega-phylogenetic approach to understand plant species distribution and coexistence at the altitudinal limits of angiosperm plant life

Aim: Plants occurring on high-alpine summits are generally expected to persist due to adaptations to extreme selective forces caused by the harshest climates where angiosperm life is known to thrive. We assessed the relative effects of this strong environmental filter and of other historical and stochastic factors driving plant community structure in very high-alpine conditions. Location: European Alps, Écrins National Park, France. Methods: Using species occurrence data collected from floristic surveys on 15 summits (2,791–4,102 m a.s.l.) throughout the Écrins range, along with existing molecular sequence data obtained from GenBank, we used a mega-phylogenetic approach to evaluate the phylogenetic structure of high-alpine plant species assemblages. We used three nested species pools and two null models to address the importance of species-specific and species-neutral processes for driving coexistence. Results: Compared with the entire species pool of the study region, alpine summits exhibited a strong signal of phylogenetic clustering. Restricting statistical sampling to environmentally and historically defined species pools reduced the significance of this pattern. However, we could not reject a model that explicitly incorporates neutral colonization and local extinction in shaping community structure for dominant plant orders. Between summits, phylogenetic turnover was generally lower than expected. Environmental drivers did not explain overall phylogenetic patterns, but we found significant geographical and climatic structure in phylogenetic diversity at finer taxonomic scales. Main conclusions: Although we found evidence for strong phylogenetic clustering within alpine summits, we were not able to reject models of species-neutral processes to explain patterns of floristic diversity. Our results suggest that plant community structure in high-alpine regions can also be shaped by neutral processes, and not through the sole action of environmental selection as traditionally assumed for harsh and stressful environments

Discovery of cryptic plant diversity on the rooftops of the Alps

International audienceHigh elevation temperate mountains have long been considered species poor owing to high extinction or low speciation rates during the Pleistocene. We performed a phylogenetic and population genomic investigation of an emblematic high-elevation plant clade (Androsace sect. Aretia, 31 currently recognized species), based on plant surveys conducted during alpinism expeditions. We inferred that this clade originated in the Miocene and continued diversifying through Pleistocene glaciations, and discovered three novel species of Androsace dwelling on different bedrock types on the rooftops of the Alps. This highlights that temperate high mountains have been cradles of plant diversity even during the Pleistocene, with in-situ speciation driven by the combined action of geography and geology. Our findings have an unexpected historical relevance: H.-B. de Saussure likely observed one of these species during his 1788 expedition to the Mont Blanc and we describe it here, over two hundred years after its first sighting