Auteurs, date et publication :
Auteurs Marie-Lise Benot , Patrick Saccone , Emmanuelle Pautrat , Rachel Vicente , Marie-Pascale Colace , Karl Grigulis , Jean-Christophe Clément , Sandra Lavorel
Publication : Ecosystems
Date : 2025
Volume : 17
Issue : 3
Pages : 458-472
Catégorie(s)
#CNRS #Lautaret #UGARésumé
The airborne plant pathogenic bacterium Pseudomonas syringae is ubiquitous in headwaters, snowpack and precipitation where its populations are genetically and phenotypically diverse. Here, we assessed its population dynamics during snowmelt in headwaters of the French Alps. We revealed a continuous and significant transport of P. syringae by these waters in which the population density is correlated with water chemistry. Via in situ observations and laboratory experiments, we validated that P. syringae is effectively transported with the snow melt and rain water infiltrating through the soil of subalpine grasslands, leading to the same range of concentrations as measured in headwaters (102–105 CFU l−1). A population structure analysis confirmed the relatedness between populations in percolated water and those above the ground (i.e. rain, leaf litter and snowpack). However, the transport study in porous media suggested that water percolation could have different efficiencies for different strains of P. syringae. Finally, leaching of soil cores incubated for up to 4 months at 8°C showed that indigenous populations of P. syringae were able to survive in subalpine soil under cold temperature. This study brings to light the underestimated role of hydrological processes involved in the long distance dissemination of P. syringae.
Auteurs, date et publication :
Auteurs Caroline L. Monteil , François Lafolie , Jimmy Laurent , Jean-Christophe Clement , Roland Simler , Yves Travi , Cindy E. Morris
Publication : Environmental Microbiology
Date : 2025
Volume : 16
Issue : 7
Pages : 2038-2052
Catégorie(s)
#CNRS #Lautaret #UGARésumé
High-alpine geomorphosites are poorly understood and developed, mostly because of the heavy constraints of high mountain areas. Meanwhile, they are geoheritage areas that are often extremely vulnerable to global warming: glaciers and permafrost areas are currently affected by major changes due to increasing air temperature. To deal with the high spatial variability of landforms and processes, research on alpine geomorphosites often needs the use of advanced methods of high-resolution topography, among which terrestrial laser scanning plays an increasingly crucial role. Carried out on some tenth of high-elevation sites across the Alps since the beginning of the 2000s, this method is particularly interesting for the recognition and development of high-alpine geomorphosites. Indeed, it can be implemented for identifying and characterizing the geomorphic objects (survey, monitoring and mapping), helping planning and protection policies and serving geotouristic development (communication about the processes involved, basis for documents).
Auteurs, date et publication :
Auteurs L. Ravanel , X. Bodin , P. Deline
Publication : Geoheritage
Date : 2025
Volume : 6
Issue : 2
Pages : 129-140
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Mountain regions are key for humanity's water supply, and their water yield depends on climatic, soil and vegetation effects. Here we explore the effects of vegetation composition and structure on the water balance of high elevation grasslands with different climatic conditions across the Alps. Using a total of 220 deep seepage collectors with intact soil-vegetation monoliths in different types of mountain grasslands in the Austrian, French and Swiss Alps, we solved the water balance equation for evapotranspiration (ET) and related the results to biomass, the abundance of certain plant functional types and structural and functional vegetation properties. While daily mean ET during the growing season was similar at all sites, ET to precipitation ratios were significantly higher and ET to potential ET ratios significantly lower at the drier French sites than at the more humid Swiss and Austrian site. Large variability of ET, seepage and soil moisture within all sites pointed at a high influence of vegetation on the water balance. While ET increased significantly with biomass at all sites, the influence of other vegetation properties was site specific. At the more humid, subalpine Austrian site the effects of vegetation on ET were stronger and more diverse than at the higher elevation Swiss site and the drier French sites, where climatic drivers dominated ET. The potential to influence ET and water yield of mountain areas by manipulating the plant canopy with systematic land management is therefore higher in regions with good growing conditions than in areas with harsh climate. Copyright © 2014 John Wiley & Sons, Ltd.
Auteurs, date et publication :
Auteurs N. Obojes , M. Bahn , E. Tasser , J. Walde , N. Inauen , E. Hiltbrunner , P. Saccone , J. Lochet , J. C. Clément , S. Lavorel , U. Tappeiner , Ch Körner
Publication : Ecohydrology
Date : 2025
Volume : 8
Issue : 4
Pages : 552-569
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Recent observations and geodetic measurements in the European Alps show that changes are occurring on rock glacier dynamics, ranging from moderate velocity variations to strong acceleration or even total collapse. These changes can be related to the ground temperature and to climate warming. In most cases, rock glaciers do not represent any serious hazard, except the instability of their surface and local rockfalls at the steep front. The surface movements, though moderate, can nevertheless cause damages to sensible infrastructures like cableways or buildings, if these are not designed to adapt to surface movements. The strong accelerations observed on some rock glaciers, however, induce a change of magnitude, and may threaten in some cases downslope areas. Thus, the presence of active or inactive rock glaciers with high ice content must be considered not only with regard to present conditions and dynamics, but with respect to possible evolutions due to climate change.
Auteurs, date et publication :
Auteurs Giorgio Lollino , Andrea Manconi , John Clague , Wei Shan , Marta Chiarle , P. Schoeneich , X. Bodin , T. Echelard , V. Kaufmann , A. Kellerer-Pirklbauer , J. -M. Krysiecki , G. K. Lieb
Date : 2025
Volume : 1
Pages : 223-227
Catégorie(s)
#CNRS #Lautaret #UGARésumé
It has long been recognized that plant species and soil microorganisms are tightly linked, but understanding how different species vary in their effects on soil is currently limited. In this study, we identified those plant characteristics (identity, specific functional traits, or resource acquisition strategy) that were the best predictors of nitrification and denitrification processes. Ten plant populations representing eight species collected from three European grassland sites were chosen for their contrasting plant trait values and resource acquisition strategies. For each individual plant, leaf and root traits and the associated potential microbial activities (i.e., potential denitrification rate [DEA], maximal nitrification rate [NEA], and NH4þ affinity of the microbial community [NHScom]) were measured at two fertilization levels under controlled growth conditions. Plant traits were powerful predictors of plant–microbe interactions, but relevant plant traits differed in relation to the microbial function studied. Whereas denitrification was linked to the relative growth rate of plants, nitrification was strongly correlated to root trait characteristics (specific root length, root nitrogen concentration, and plant affinity for NH4þ) linked to plant N cycling. The leaf economics spectrum (LES) that commonly serves as an indicator of resource acquisition strategies was not correlated to microbial activity. These results suggest that the LES alone is not a good predictor of microbial activity, whereas root traits appeared critical in understanding plant–microbe interactions.
Auteurs, date et publication :
Auteurs Amélie A. M. Cantarel , Thomas Pommier , Marie Desclos-Theveniau , Sylvain Diquélou , Maxime Dumont , Fabrice Grassein , Eva-Maria Kastl , Karl Grigulis , Philippe Laîné , Sandra Lavorel , Servane Lemauviel-Lavenant , Emmanuelle Personeni , Michael Schloter , Franck Poly
Publication : Ecology
Date : 2025
Volume : 96
Issue : 3
Pages : 788-799
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Background and aims Rhizodeposition plays an important role in mediating soil nutrient availability in ecosystems. However, owing to methodological difficulties (i.e., narrow zone of soil around roots, rapid assimilation by soil microbes) fertility-induced changes in rhizodeposition remain mostly unknown.
Auteurs, date et publication :
Auteurs Florence Baptist , Iker Aranjuelo , Nicolas Legay , Luis Lopez-Sangil , Gemma Molero , Pere Rovira , Salvador Nogués
Publication : Plant and Soil
Date : 2025
Volume : 394
Issue : 1-2
Pages : 391-406
Catégorie(s)
#CNRS #Lautaret #UGARésumé
The full-scale avalanche test site at Lautaret Pass in the southern French Alps has been used by IRSTEA-Cemagref Research Institute since 1972. Over recent years, two avalanche paths have been used routinely to release avalanches and study avalanche dynamics and interactions between avalanches and obstacles. Avalanche flows are generally dense and dry, sometimes with a powder cloud on top. Main avalanche path no. 2 is dedicated to studies on avalanche dynamics. Within the flow of the avalanche, flow height and vertical profiles of pressure and velocity are measured along a 3.5 m tripod. The snow volume released in the release zone is quantified by differential analysis of laser scanning measurements performed before and after triggering. High-speed positioning of the avalanche front along the track is carried out by terrestrial oblique photogrammetry. Above the dense layer, the upper layer of the avalanche is characterized by particle and air flux measurements. Avalanche path no. 1 is smaller in size and particularly well-suited to experiments on structures exposed to small to medium-size avalanches (b1000 m3). A macroscopic sensor structure consisting of a one square-meter plate supported by a 3.5 m high steel cantilever beam is fixed in the ground, facing the avalanche. Impact pressures are reconstructed from the beam deformations and avalanche velocity is measured by optical sensors. For these experimental devices dedicated to improving our understanding of avalanche physics, a national and international partnership has been developed over the years, including INSA de Lyon, CNRS and Université Joseph Fourier (France), Aalto University (Finland), Nagoya University (Japan), Boku University (Austria) and IGEMA (Bolivia).
Auteurs, date et publication :
Auteurs Emmanuel Thibert , Hervé Bellot , Xavier Ravanat , Frédéric Ousset , Gaëtan Pulfer , Mohamed Naaim , Pascal Hagenmuller , Florence Naaim-Bouvet , Thierry Faug , Koichi Nishimura , Yoichi Ito , Djebar Baroudi , Alexander Prokop , Peter Schön , Alvaro Soruco , Christian Vincent , Ali Limam , Raphaële Héno
Publication : Cold Regions Science and Technology
Date : 2025
Volume : 115
Pages : 30-41
Catégorie(s)
#CNRS #Lautaret #UGARésumé
In alpine and arctic ecosystems, the snowpack has been shown to insulate soils from the winter climatic harshness. Ongoing climate change modifies snowpack quantity and quality, but the consequences of these changes on the soil functioning remain largely unknown. We benefited from a subalpine landscape of the French Alps where, 700 years ago, agricultural practices led to the formation of terraces. Subsequently, on each terrace, snow thickness patterns significantly differed between the bank and the front areas inducing strong divergence in their soil microclimatic conditions. Using this framework, we measured abundances and activities of nitrifiers and denitrifiers, together with a set of environmental variables, on three grassland terraces between December and May to test the following hypotheses: (i) soil N-related microbial abundances and activities are sensitive to soil microclimatic variations and differ along the terrace snow depth gradient during winter, (ii) a thicker snowpack favors higher abundances and activities, and (iii) the driving forces for nitrification and denitrification abundances and activities vary along the snow depth gradient. Our results showed significantly and changing N-related microbial activities and abundances during winter despite partly frozen soils, and suggested the selection and/or adaptation of psychrophilic microbial communities. Moreover, activities as well as abundances of nitrifiers and denitrifiers were significantly higher under a weak or absent snowpack during winter, and mostly related to soil water content and soil surface temperature according to our models. We suggest that strongly variable soil abiotic conditions at the front stations enabled the release of nutrients from soil organic and inorganic compounds favoring psychrophilic bacterial abundances and activities. Contrastingly, a thicker and permanent snowpack maintained circum-zero soil temperatures during winter which limited the microbial community's turnover and release of organic and inorganic N. This created N-limited conditions and N-competition between microbial populations resulting in lower abundances and activities. Overall, changes in the snowpack depth strongly affect the soil microbial functioning of subalpine grasslands with potential consequences on nutrient dynamic and other trophic levels.
Auteurs, date et publication :
Auteurs My-Dung Jusselme , Patrick Saccone , Lucie Zinger , Mathieu Faure , Xavier Le Roux , Nadine Guillaumaud , Lionel Bernard , Jean-Christophe Clement , Franck Poly
Publication : Soil Biology and Biochemistry
Date : 2025
Volume : 92
Pages : 27-37
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Methods In a greenhouse experiment, soil legacy effects on Lolium perenne were examined, first under optimal conditions, and subsequently during and after drought. We used subalpine grassland soils previously cultivated for two years with grass communities of distinct functional composition, and subjected to combinations of climatic stress and simulated management.
Results The soil legacy of climatic stress increased biomass production of Lolium perenne and its resistance and recovery to a new drought. This beneficial effect resulted from higher nutrient availability in soils previously exposed to climatic stresses due to lower competitive abilities and resistance of microbial communities to a new drought. This negative effect on microbial communities was strongest in soils from previously cut and fertilized grasslands or dominated by conservative grasses.
Conclusion In subalpine grasslands more frequent climatic stresses could benefit fodder production in the short term, but threaten ecosystem functioning and the maintenance of traditional agricultural practices in the long term.
Auteurs, date et publication :
Auteurs Nicolas Legay , Gabin Piton , Cindy Arnoldi , Lionel Bernard , Marie-Noëlle Binet , Bello Mouhamadou , Thomas Pommier , Sandra Lavorel , Arnaud Foulquier , Jean-Christophe Clément
Publication : Plant and Soil
Date : 2025
Volume : 424
Issue : 1-2
Pages : 233-254