Résumé
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
Catégorie(s)
#CNRS #Lautaret #UGARésumé
The cessation of mowing in subalpine grasslands promotes the dominance of Festuca paniculata leading to the reduction in plant diversity. Moreover, it affects positively the abundance of Epichlo€e sp. inhabiting F. paniculata leaves and negatively the soil density of arbuscular mycorrhizal fungi (AMF). We explored how the cessation of mowing influences root AMF communities in F. paniculata and the neighboring plants, and Epichlo€e sp alkaloids. Thirteen AMF operational taxonomical units were found. The neighboring plants affected positively the abundances of Aalpin and GLOM_7 whereas the interaction plant/ management type influenced significantly Claroide_1, GLOM_1 and GLOM_7. The N-formylnorloline, produced by Epichlo€e sp. increased in unmown grassland. Hence, the cessation of mowing, coinciding with the high abundance of endophyte alkaloid, affected root-associated AMF with differential responses at the abundance level. The N-formylnorloline could be one compound underpinning the dynamic of plant diversity with a resulting structuration of AMF in subalpine grasslands.
Auteurs, date et publication :
Auteurs Marie-Noëlle Binet , Diederik van Tuinen , Florence Souard , Lucile Sage , Sophie Périgon , Christiane Gallet , Nicolas Legay , Sandra Lavorel , Bello Mouhamadou
Publication : Fungal Ecology
Date : 2025
Volume : 25
Pages : 14-21
Catégorie(s)
#CNRS #Lautaret #UGAAuteurs, date et publication :
Auteurs Nina Dombrowski , Klaus Schlaeppi , Matthew T Agler , Stéphane Hacquard , Eric Kemen , Ruben Garrido-Oter , Jörg Wunder , George Coupland , Paul Schulze-Lefert
Publication : The ISME Journal
Date : 2025
Volume : 11
Issue : 1
Pages : 43-55
Catégorie(s)
#CNRS #Lautaret #UGAAuteurs, date et publication :
Auteurs Loïc Chalmandrier , Tamara Münkemüller , Marie-Pascale Colace , Julien Renaud , Serge Aubert , Bradley Z. Carlson , Jean-Christophe Clément , Nicolas Legay , Gilles Pellet , Amélie Saillard , Sébastien Lavergne , Wilfried Thuiller , Meghan Avolio
Publication : Journal of Ecology
Date : 2025
Volume : 105
Issue : 1
Pages : 277-287
Catégorie(s)
#CNRS #Lautaret #UGARésumé
We present a multidisciplinary approach to document the vegetation and landscape of Upper Guisane Valley around the Lautaret Pass area in the French Southwestern Alps since 7200 calyr BP. We combined pollen analysis in a peat bog (at 2044 m) with a leaf imprint study in two nearby travertine systems (at 2100 and 1950 m). During the last 7200 years, there was an open landscape with scarce trees such asconifers including Larix decidua Mill., Pinus spp., and Abies alba Mill. 2100 m was the highest altitude where fossils of A. alba Mill. have been reported in the Guisane Valley. These results, according to the pollen record of anthropogenic indicators and an increasing biodiversity of grasslands, suggest a human presence in the pass area since ca 6500 years with a preRoman deforestation. This human impact has become maximum from 1100 calyr BP to present, resulting from cereal crop agriculture and deforestation. The comparative study of the different records confirmed the role played by the exposition in the forest dynamics of the alpine valleys during the Holocene.
Auteurs, date et publication :
Auteurs Anne-Lise Cabanat , Fernand David , Jean-Louis Latil , Christophe Perrier , Serge Aubert
Publication : Review of Palaeobotany and Palynology
Date : 2025
Volume : 246
Pages : 32-43
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Earlier snowmelt changes spring stress exposure and growing-season length, possibly causing shifts in plant species dominance. If such shifts involve trees, this may lead to changes in treeline position. We hypothesized that earlier snowmelt would negatively affect the performance of tree seedlings near the treeline due to higher spring stress levels, but less so if seedlings were protected from the main stress factors of night frosts and excess solar radiation. We exposed seedlings of five European treeline tree species: Larix decidua, Picea abies, Pinus cembra, Pinus uncinata, and Sorbus aucuparia to two snow-cover treatments (early and late melting, with about two weeks difference) combined with reduced sky exposure during the day (shading) or night (night warming), repeated in two years, at a site about 200 m below the regional treeline elevation. Physiological stress levels (as indicated by lower Fv/Fm) in the first weeks after emergence from snow were higher in early-emerging seedlings. As expected, shade reduced stress, but contrary to expectation, night warming did not. However, early- and late-emerging seedlings did not differ overall in their growth or survival, and the interaction with shading was inconsistent between years. Overall, shading had the strongest effect, decreasing stress levels and mortality (in the early-emerging seedlings only), but also growth. A two-week difference in snow-cover duration did not strongly affect the seedlings, although even smaller differences have been shown to affect productivity in alpine and arctic tundra vegetation. Still, snowmelt timing cannot be discarded as important for regeneration in subalpine conditions, because (1) it is likely more critical in very snow-rich or snow-poor mountains or landscape positions; and (2) it can change (sub)alpine vegetation phenology and productivity, thereby affecting plant interactions, an aspect that should be considered in future studies.
Auteurs, date et publication :
Auteurs Maaike Y. Bader , Hannah Loranger , Gerhard Zotz , Glenda Mendieta-Leiva
Publication : Forests
Date : 2025
Volume : 9
Issue : 1
Pages : 12