Résumé
Many studies have shown effects of plants species on fungal communities, but these are often confounded with soil effects. Thus, the specific role of plant species in structuring rhizospheric and soil fungal communities is poorly described. Our study used microcosms in which plants were grown under artificial conditions to bridge this gap. Two perennial grasses dominating subalpine grasslands, Festuca paniculata and Dactylis glomerata, were grown at two levels of fertilization on standard soil. Fungal communities were determined by 454 pyrosequencing of the internal transcribed spacer 1 region. Among the fungal communities characterized by the primers used, original communities were associated to each plant species and also diverged between rhizosphere and bulk soils within each plant species, though there were no significant fertilization effects. Differences regarded global composition of the fungal communities and abundant molecular operational taxonomic units (MOTUs). Both plant species and location effects were reflected more in the abundance than in the composition of MOTUs. The observed differences in fungal communities coincide with differing strategies of plant root growth, with D. glomerata having greater root mass, length, and area than F. paniculata. Our study, by dissociating soil effects from plant effects, demonstrated that plant species exert a key control on soil fungi. We suggest that such effects may be linked to inter-specific differences in root traits and their consequences on nitrogen uptake.
Auteurs, date et publication :
Auteurs B. Mouhamadou , J. Puissant , E. Personeni , M. Desclos-Theveniau , E. M. Kastl , M. Schloter , L. Zinger , J. Roy , R. A. Geremia , S. Lavorel
Publication : Biology and Fertility of Soils
Date : 2013
Volume : 49
Issue : 8
Pages : 1131-1139
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Aims In subalpine grasslands, litter decomposition controls soil nutrient availability and is highly sensitive to increasing intensity and frequency of extreme climate events, potentially impacting grasslands diversity and functioning. Here, we assessed the effects of early snowmelt and summer drought on decomposition, and how these were modulated by agricultural management.
Auteurs, date et publication :
Auteurs Lionel Bernard , Arnaud Foulquier , Christiane Gallet , Sandra Lavorel , Jean-Christophe Clément
Publication : Plant and Soil
Date : 2025
Volume : 435
Issue : 1-2
Pages : 225-238
Catégorie(s)
#CNRS #Lautaret #UGARésumé
In French subalpine grasslands, cessation of mowing promotes dominance of Festuca paniculata, which alters plant diversity and ecosystem functioning. One of the mechanisms underpinning such effects may be linked to simultaneous changes in the abundance of fungal symbionts such as endophytes and arbuscular mycorrhizal fungi. In field conditions, mowing reduced the abundance of the endophyte Neotyphodium sp. in leaves of F. paniculata by a factor of 6, and increased mycorrhizal densities by a factor of 15 in the soil. In greenhouse experiments, the mycorrhizal colonization of Trifolium pratense and Allium porrum increased 3- fold and 3.8- fold respectively in mown vs unmown grassland soil. Significantly reduced growth of the two host plants was also observed on soil from the unmown grassland. Such opposite effects of mowing on the two functional groups of fungal symbionts could suggest interactions between these two groups, which in turn could contribute to structuring plant communities in subalpine grasslands.
Auteurs, date et publication :
Auteurs M.N. Binet , L. Sage , C. Malan , J.C. Clément , D. Redecker , D. Wipf , R.A. Geremia , S. Lavorel , B. Mouhamadou
Publication : Fungal Ecology
Date : 2025
Volume : 6
Issue : 4
Pages : 248-255
Catégorie(s)
#CNRS #Lautaret #UGARésumé
European mountain grasslands are increasingly affected by land-use changes and climate, which have been suggested to exert important controls on grassland carbon (C) and nitrogen (N) pools. However, so far there has been no synthetic study on whether and how land-use changes and climate interactively affect the partitioning of these pools amongst the different grassland compartments. We analyzed the partitioning of C and N pools of 36 European mountain grasslands differing in land-use and climate with respect to above- and belowground phytomass, litter and topsoil (top 23 cm). We found that a reduction of management intensity and the abandonment of hay meadows and pastures increased above-ground phytomass, root mass and litter as well as their respective C and N pools, concurrently decreasing the fractional contribution of the topsoil to the total organic carbon pool. These changes were strongly driven by the cessation of cutting and grazing, a shift in plant functional groups and a related reduction in litter quality. Across all grasslands studied, variation in the impact of land management on the topsoil N pool and C/N-ratio were mainly explained by soil clay content combined with pH. Across the grasslands, below-ground phytomass as well as phytomass- and litter C concentrations were inversely related to the mean annual temperature; furthermore, C/N-ratios of phytomass and litter increased with decreasing mean annual precipitation. Within the topsoil compartment, C concentrations decreased from colder to warmer sites, and increased with increasing precipitation. Climate generally influenced effects of land use on C and N pools mainly through mean annual temperature and less through mean annual precipitation. We conclude that site-specific conditions need to be considered for understanding the effects of land use and of current and future climate changes on grassland C and N pools.
Auteurs, date et publication :
Auteurs Julia Seeber , Erich Tasser , Dagmar Rubatscher , Ingrid Loacker , Sandra Lavorel , T. Matthew Robson , Manuela Balzarolo , Nuria Altimir , Matthias Drösler , Loris Vescovo , Sonja Gamper , Peter Barančok , Tomasz Staszewski , Georg Wohlfahrt , Alexander Cernusca , M. -Teresa Sebastia , Ulrike Tappeiner , Michael Bahn
Publication : Science of The Total Environment
Date : 2025
Volume : 822
Pages : 153380
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Understanding how photosynthesis responds to the environment is crucial for improving plant production and maintaining biodiversity in the context of global change. Covering all aspects of photosynthesis, from basic concepts to methodologies, from the organelle to whole ecosystem levels, this is an integrated guide to photosynthesis in an environmentally dynamic context. Focusing on the ecophysiology of photosynthesis - how photosynthesis varies in time and space, responds and adapts to environmental conditions and differs among species within an evolutionary context - the book features contributions from leaders in the field. The approach is interdisciplinary and the topics covered have applications for ecology, environmental sciences, agronomy, forestry and meteorology. It also addresses applied fields such as climate change, biomass and biofuel production and genetic engineering, making a valuable contribution to our understanding of the impacts of climate change on the primary productivity of the globe and on ecosystem stability.
Auteurs, date et publication :
Auteurs F. Berninger , P. Streb , I. Ensminger
Date : 2012
Pages : 488-505
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Rock glaciers, usually preserved in periglacial environments of cold-climate high-relief regions, are useful (palaeo)climate indicators. In the European Alps, numerous studies have focused on describing these geomorphological features. However, very few have attempted directly dating them. This lack of measurement is particularly evident in the French Alps. To fill this gap, we performed Cosmic Ray Exposure (CRE) dating through beryllium-10 (10Be) on 10 granitic rock samples collected from two relict rock glaciers, hereafter referred as RG1 and RG2, located at col du Lautaret in the French Alps. This first CRE dating of rock glaciers in the French Alps yielded mean ages of 11.8 ± 0.5 kyrs and 11.6 ± 0.6 kyrs for RG1 and RG2, respectively. While RG2 is clearly a talus-derived rock glacier, the origin of RG1 is less clear. It could potentially be talus-derived, glacier-derived or of mixed origin. The 10Be ages indicate that both rock glaciers became inactive during the transition between the Younger Dryas and the onset of the Holocene, consistently with other studies in the Northern Hemisphere. Considering surface velocity measurements carried out since the 1980s on neighbouring rock glaciers, we hypothesise that the rock glaciers were formed either during the Younger Dryas or slightly earlier, between the Heinrich Stadial 1 and the Younger Dryas. During this period, we estimated temperatures ~3.6 °C lower than the 1980s and precipitation up to 30% lower than at present.
Auteurs, date et publication :
Auteurs Joanna Charton , Deborah Verfaillie , Vincent Jomelli , Bernard Francou
Publication : Geomorphology
Date : 2025
Volume : 394
Pages : 107962
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Alpine treelines globally may move upslope due to climatic warming. Such movement would need, as the first steps, seed germination and seedling establishment ab
Auteurs, date et publication :
Auteurs Hannah Loranger , Gerhard Zotz , Maaike Y. Bader
Publication : AoB PLANTS
Date : 2016
Volume : 8
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Subalpine grassland ecosystems are important from biodiversity, agriculture, and touristic perspectives but their resilience to seasonally occurring climatic extremes is increasingly challenged with climate change, accelerating their vulnerability to tipping points. Microbial communities, which are central in ecosystem functioning, are usually considered as more resistant and highly resilient to such extreme events due to their functional redundancy and strong selection in residing habitats. To investigate this, we explored soil microbial responses upon recurrent summer droughts associated with early snowmelt in subalpine grasslands mesocosms set-up at the Lautaret Pass (French Alps). Potential respiration, nitrification and denitrification were monitored over a period of two growing seasons along with quantification of community gene abundances of total bacteria as well as (de)nitrifiers. Results revealed that droughts had a low and short-term adverse impact on bacterial total respiration supporting their hypothesized high resilience, i.e., resistance and ability to recover. Nitrification and abundances of the corresponding functional guilds showed relatively strong resistance to summer droughts but declined in response to early snowmelt. This triggered a cascading effect on denitrification but also on abundances of denitrifying communities which recovered from all climatic extremes except from the summer droughts where nitrifiers were collapsed. Denitrification and respective functional groups faced high impact of applied stresses with strong reduction in abundance and activity of this specialized community. Although, consequently lower microbial competition for nitrate may be positive for plant biomass production, warnings exist when considering the potential nitrogen leaching from these ecosystems as well as risks of greenhouses gases emission such as N2O.
Auteurs, date et publication :
Auteurs Farhan Hafeez , Lionel Bernard , Franck Poly , Jean-Christophe Clément , Thomas Pommier
Date : 2021
Pages : 2021.03.15.435477
Catégorie(s)
#CNRS #Lautaret #UGARésumé
In the French Alps, Soldanella alpina (S. alpina) grow under shade and sun conditions during the vegetation period. This species was investigated as a model for the dynamic acclimation of shade leaves to the sun under natural alpine conditions, in terms of photosynthesis and leaf anatomy. Photosynthetic activity in sun leaves was only slightly higher than in shade leaves. The leaf thickness, the stomatal density and the epidermal flavonoid content were markedly higher, and the chlorophyll/flavonoid ratio was significantly lower in sun than in shade leaves. Sun leaves also had a more oxidised plastoquinone pool, their PSII efficiency in light was higher and their non-photochemical quenching (NPQ) capacity was higher than that of shade leaves. Shade-sun transferred leaves increased their leaf thickness, stomatal density and epidermal flavonoid content, while their photosynthetic activity and chlorophyll/flavonoid ratio declined compared to shade leaves. Parameters indicating protection against high light and oxidative stress, such as NPQ and ascorbate peroxidase, increased in shade-sun transferred leaves and leaf mortality increased. We conclude that the dynamic acclimation of S. alpina leaves to high light under alpine conditions mainly concerns anatomical features and epidermal flavonoid acclimation, as well as an increase in antioxidative protection. However, this increase is not large enough to prevent damage under stress conditions and to replace damaged leaves.
Auteurs, date et publication :
Auteurs Anne-Claire Talhouët , Sylvie Meyer , Xavier Baudin , Peter Streb
Publication : Physiologia Plantarum
Date : 2025
Volume : 168
Issue : 3
Pages : 563-575
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Phenolic compounds play important ecological roles in alpine plants such as offering efficient UV protection at high level of incident sunlight. Methods to study those compounds are limited, as they require sophisticated analytical tools and are time-consuming. An alternative and portable device—Dualex©—has been recently developed to estimate the plant epidermal flavonoids by fluorescence sensing. Here, we assessed if the Dualex device accurately estimates the phenolic contents of three alpine plant species along an elevational gradient and be an alternative to the commonly used chemical methods. We characterized their leaf epidermal absorbance measured by the Dualex device, total phenol content assessed by the Folin–Ciocalteu assay and total flavonoid content estimated by high-performance liquid chromatography. The results showed that leaf epidermal absorbance was slightly positively correlated to total phenols for Rhododendron ferrugineum and Dryas octopetala, but not for Vaccinium myrtillus and to total flavonoids for the first species, but not for the two others. The leaf epidermal absorbance estimated by the Dualex device is not an accurate and universal predictor of total phenols or total flavonoid contents for alpine plant species. The limitations of this optical method could be mainly explained by the high intraspecific variability of plant chemical composition in heterogeneous environmental conditions met in alpine areas. We thus recommend a cautious use of this device to avoid misinterpretations.
Auteurs, date et publication :
Auteurs Tiphaine Lefebvre , Annie Millery-Vigues , Christiane Gallet
Publication : Alpine Botany
Date : 2016
Volume : 126
Issue : 2
Pages : 177-185