Auteurs, date et publication :
Auteurs Isabelle Boulangeat , Damien Georges , Cédric Dentant , Richard Bonet , Jérémie Van Es , Sylvain Abdulhak , Niklaus E. Zimmermann , Wilfried Thuiller
Publication : Ecography
Date : 2025
Volume : 37
Issue : 12
Pages : 1230-1239
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Mountain environments are marked by an altitudinal zonation of habitat types. They are home to a multitude of terrestrial green algae, who have to cope with abiotic conditions specific to high elevation, e.g., high UV irradiance, alternating desiccation, rain and snow precipitations, extreme diurnal variations in temperature and chronic scarceness of nutrients. Even though photosynthetic green algae are primary producers colonizing open areas and potential markers of climate change, their overall biodiversity in the Alps has been poorly studied so far, in particular in soil, where algae have been shown to be key components of microbial communities. Here, we investigated whether the spatial distribution of green algae followed the altitudinal zonation of the Alps, based on the assumption that algae settle in their preferred habitats under the pressure of parameters correlated with elevation. We did so by focusing on selected representative elevational gradients at distant locations in the French Alps, where soil samples were collected at different depths. Soil was considered as either a potential natural habitat or temporary reservoir of algae. We showed that algal DNA represented a relatively low proportion of the overall eukaryotic diversity as measured by a universal Eukaryote marker. We designed two novel green algae metabarcoding markers to amplify the Chlorophyta phylum and its Chlorophyceae class, respectively. Using our newly developed markers, we showed that elevation was a strong correlate of species and genus level distribution. Altitudinal zonation was thus determined for about fifty species, with proposed accessions in reference databases. In particular, Planophila laetevirens and Bracteococcus ruber related species as well as the snow alga Sanguina genus were only found in soil starting at 2,000 m above sea level. Analysis of environmental and bioclimatic factors highlighted the importance of pH and nitrogen/carbon ratios in the vertical distribution in soil. Capacity to grow heterotrophically may determine the Trebouxiophyceae over Chlorophyceae ratio. The intensity of freezing events (freezing degree days), proved also determinant in Chlorophyceae distribution. Guidelines are discussed for future, more robust and precise analyses of environmental algal DNA in mountain ecosystems and address green algae species distribution and dynamics in response to environmental changes.
Auteurs, date et publication :
Auteurs Adeline Stewart , Delphine Rioux , Fréderic Boyer , Ludovic Gielly , François Pompanon , Amélie Saillard , Wilfried Thuiller , Jean-Gabriel Valay , Eric Maréchal , Eric Coissac
Publication : Frontiers in Plant Science
Date : 2025
Volume : 12
Catégorie(s)
#ANR-Citation #CNRS #Lautaret #UGARésumé
Snowmelt in alpine ecosystems brings ample water, and together with above-freezing temperatures, initiates plant growth. In this scenario, rapid activation of photosynthesis is essential for a successful life-history strategy. But, strong solar radiation in late spring enhances the risk of photodamage, particularly before photosynthesis is fully functional. We compared the photoprotective strategy of five alpine forbs: one geophyte not particularly specialised in subnival life (Crocus albiflorus) and four wintergreens differing in their degree of adaptation to subnival life, from least to most specialised: Gentiana acaulis, Geum montanum, Homogyne alpina and Soldanella alpina. We used distance to the edge of snow patches as a proxy to study time-dependent changes after melting. We postulated that the photoprotective response of snowbed specialists would be stronger than of more-generalist alpine meadow species. Fv/Fm was relatively low across wintergreens and even lower in the geophyte C. albiflorus. This species also had the largest xanthophyll-cycle pool and lowest tocopherol and flavonoid glycoside contents. After snow melting, all the species progressively activated ETR, but particularly the intermediate snowbed species G. acaulis and G. montanum. The photoprotective responses after snowmelt were idiosyncratic: G. montanum rapidly accumulated xanthophyll-cycle pigments, tocopherol and flavonoid glycosides; while S. alpina showed the largest increase in plastochromanol-8 and chlorophyll contents and the greatest changes in optical properties. Climate warming scenarios might shift the snowmelt date and consequently alter the effectiveness of photoprotection mechanisms, potentially changing the fitness outcome of the different strategies adopted by alpine forbs.
Auteurs, date et publication :
Auteurs Beatriz Fernández-Marín , Ana Sáenz-Ceniceros , Twinkle Solanki , Thomas Matthew Robson , José Ignacio García-Plazaola
Publication : Physiologia Plantarum
Date : 2025
Volume : 172
Issue : 3
Pages : 1506-1517
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Many new taxons have been discovered in HautesAlpes (southern alps, France) since 1994, date of publishing of a botanical atlas over this territory (CHAS, 1994). New stations have also been discovered for noteworthy species in regard to their rarity or distribution. Consequently, 104 new taxons are mentioned for the first time in the studied zone. The majority of these new species (43%) has a ruderal strategy, and 18% of them are neophytes. Besides, 6 of these new mentions are due to taxonomics reviewing of local populations (Arum cylindraceum, Cynoglossum montanum, Fritillaria burnatii, Linaria vulgaris, Luzula alpina, Schoenoplectus lacustris). The reviewing of the local distribution of 98 taxons is also lead, taking intout acount the rarety of these species or the originality of the new data. Finally, 12 species escaped from the Lautaret alpine garden (2100 m) are presented in regard to their long term naturalization possibility.
Auteurs, date et publication :
Auteurs Cédric Dentant , Franck le Driant , Jérémie Van Es , Lionel Ferrus , Luc Garraud , Sylvain Abdulhak , Rolland Douzet
Publication : Le Monde des plantes
Date : 2025
Volume : 508
Pages : 3-26
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Aim To incorporate changes in alpine land cover (tree line shift, glacier retreat and primary succession) into species distribution model (SDM) predictions for a selection of 31 high-elevation plants.
Auteurs, date et publication :
Auteurs Bradley Z. Carlson , Damien Georges , Antoine Rabatel , Christophe F. Randin , Julien Renaud , Anne Delestrade , Niklaus E. Zimmermann , Philippe Choler , Wilfried Thuiller , Mathieu Rouget
Publication : Diversity and Distributions
Date : 2025
Volume : 20
Issue : 12
Pages : 1379-1391
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Ecosystems support the adaptation of societies to global changes through their contributions to people's quality of life. Ecosystem-based adaptation (EBA) implementation remains a challenge and will require changes of practices, structures and processes underpinning human and nature interactions, also considered as co-production of nature’s contributions to adaptation (NCA). We analysed the levers required to implement EBA to reach a future desired by stakeholders of a mountain social-ecological system in the French Alps. Using a participatory backcasting scenario approach and a serious game, local stakeholders were invited to design a desired vision for their region in 2040 and reflect on strategies and levers for reaching it. We analysed co-production actions required to achieve adaptation objectives aligned with the vision. We then assessed how local communities can leverage these actions to navigate a desired adaptation pathway. EBA and landscape multifunctionality are critical to achieve stakeholders’ vision. EBA require substantial adjustments, transformations, or new co-production actions, but natural capital was not a limiting factor for adaptation. Synergies among multiple co-production actions create windows of opportunity for local communities to achieve their vision through the combination of social levers. However, most powerful levers, like collaborative decision-making or common strategy design, appeared the most difficult to activate. EBA is mainly constrained here by social barriers reflecting the lack of collaboration and communication among stakeholders. Recognizing potential contributions of ecosystems to adaptation by maintaining and developing NCA supply can help communities to re-structure and re-think their local social-ecological system to achieve desired and sustainable pathways.
Auteurs, date et publication :
Auteurs Enora Bruley , Bruno Locatelli , Matt J. Colloff , Nicolas Salliou , Thibault Métris , Sandra Lavorel
Publication : Environmental Science & Policy
Date : 2021
Volume : 124
Pages : 567-579
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Snow depth estimation derived from high-resolution digital elevation models (DEMs) can lead to improved understanding of the spatially highly heterogeneous nature of snow distribution, as well as help us improve our knowledge of how snow patterns influence local geomorphic processes. Slope deformation processes such as permafrost creep can make it challenging to acquire a snow-free DEM that matches the sub-snow topography at the time of the associated snow-covered DEM, which can cause errors in the computed snow depths. In this study, we illustrate how modelling changes in the sub-snow topography can reduce errors in snow depths derived from DEM differencing in an area of permafrost creep. To model the sub-snow topography, a surface deformation model was constructed by performing non-rigid registration based on B-splines of two snow-free DEMs. Seasonal variations in creep were accounted for by using an optimization approach to find a suitable value to scale the deformation model based on in-situ snow depth measurements or the presence of snow-free areas corresponding to the date of the snow-covered DEM. This scaled deformation model was used to transform one of the snow-free DEMs to estimate the sub-snow topography corresponding to the date of the snow-covered DEM. The performance of this method was tested on an active rock glacier in the southern French Alps for two surveys dates, which were conducted in the winter and spring of 2017.
Auteurs, date et publication :
Auteurs Jason Goetz , Paul Fieguth , Keyvan Kasiri , Xavier Bodin , Marco Marcer , Alexander Brenning
Publication : Remote Sensing of Environment
Date : 2025
Volume : 231
Pages : 111275
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Demographic compensation arises when vital rates change in opposite directions across populations, buffering the variation in population growth rates, and is a mechanism often invoked to explain the stability of species geographic ranges. However, studies on demographic compensation have disregarded the effects of temporal variation in vital rates and their temporal correlations, despite theoretical evidence that stochastic dynamics can affect population persistence in temporally varying environments. We carried out a seven-year-long demographic study on the perennial plant Arabis alpina (L.) across six populations encompassing most of its elevational range. We discovered demographic compensation in the form of negative correlations between the means of plant vital rates, but also between their temporal coefficients of variation, correlations and elasticities. Even if their contribution to demographic compensation was small, this highlights a previously overlooked, but potentially important, role of stochastic processes in stabilising population dynamics at range margins.
Auteurs, date et publication :
Auteurs Marco Andrello , Pierre de Villemereuil , Marta Carboni , Delphine Busson , Marie-Josée Fortin , Oscar E. Gaggiotti , Irène Till‐Bottraud
Publication : Ecology Letters
Date : 2025
Volume : 23
Issue : 5
Pages : 870-880
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Methods: Our approach gradually constrains null models by: (1) filtering out species not able to survive in the regional conditions in order to reduce the spatial scale, and (2) shuffling species only within lineages of different ages to reduce the evolutionary scale of the analysis. We first tested and validated this approach using simulated communities. We then applied it to study the functional diversity patterns of the leaf–height–seed strategy of plant communities in the French Alps.
Results: Using simulations, we found that reducing the spatial scale correctly detected a signature of competition (functional divergence) even when environmental filtering produced an overlaying signal of functional convergence. However, constraining the evolutionary scale did not change the identified functional diversity patterns. In the case study of alpine plant communities, investigating scale effects revealed that environmental filtering had a strong influence at larger spatial and evolutionary scales and that neutral processes were more important at smaller scales. In contrast to the simulation study results, decreasing the evolutionary scale tended to increase patterns of functional divergence.
Conclusion: We argue that the traditional null model approach can only identify a single main process at a time and suggest to rather use a family of null models to disentangle intertwined assembly processes acting across spatial and evolutionary scales.
Auteurs, date et publication :
Auteurs L. Chalmandrier , T. Münkemüller , L. Gallien , F. de Bello , F. Mazel , S. Lavergne , W. Thuiller , Rasmus Ejrnaes
Publication : Journal of Vegetation Science
Date : 2025
Volume : 24
Issue : 5
Pages : 853-864
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Cushion plants have long fascinated botanists for their ability to cope with extreme environments in most mountains and arctic regions of the world. One century ago, a first worldwide catalogue of species forming cushions was published by Hauri and Schröter (Bot Jahrb Syst Pflanzengesch Pflanzengeogr 50:618–656, 1914). Here, we defined a simplified typology of cushion plants and updated the worldwide catalogue of cushion species, along with information on their geographic distribution. This compilation was based on available information in floras and catalogues but also in efloras and virtual encyclopedias, which were screened using automated database queries. We established a list of 1,309 cushion-forming species distributed in 272 genera and 63 families of angiosperms. Compact cushions are represented by 678 species, among which 587 species exhibit a hemispherical shape, and 91 species exhibit a flat to mat shape. We found 398 species forming non-compact hemispherical cushions. The list of cushion species has significantly increased since Hauri and Shröter, due to the description of new species, updated regional inventories, and improved access to electronic databases. Uncertainties in the delineation of the cushion life form are discussed, notably for non-compact growth forms. A website has been launched to display the catalogue and enable a collaborative improvement of the database (http://www.cushionplants.eu/). The distribution of the species is presented on the basis of the world geographical scheme for recording plant distributions and global biodiversity information facility data. This catalogue will serve as a reference database for further analyses on the biogeography and evolutionary history of cushion plants and arctico-alpine biotas.
Auteurs, date et publication :
Auteurs Serge Aubert , Florian Boucher , Sébastien Lavergne , Julien Renaud , Philippe Choler
Publication : Alpine Botany
Date : 2014
Volume : 124
Issue : 1
Pages : 59-70