Résumé
Frost stress is the main factor determining the distribution of plants at high latitude and elevation. Although species are currently adapted to their highest location, climate change is likely to modify their adaptation strategies in the face of climatic stress. This is particularly true for trees at their altitudinal limit, where the number of freeze-thaw episodes is likely to increase.
To monitor the exposure to frost stress and its impact on tree growth, we monitored five contrasted species (Acer pseudoplatanus, Betula pendula, Larix decidua, Picea abies and Sorbus aucuparia) over a 3-year period in the Lautaret alpine garden (2100 m asl) by using an automatic, autonomous, connected micro-dendrometer. These systems continuously measured (every 30 minutes or 1 hour) both variations in trunk diameter and air temperature in the vicinity of the measurement, making it possible to determine the number and duration of frost cycles, growth periods and ecophysiological functioning of the species monitored in these extreme conditions. We observed specific responses of the trees, in relation to their wood anatomy and leaf phenology
Auteurs, date et publication :
Auteurs Thierry Ameglio , Katline Charra-Vaskou , Loïc Francon , Lucie Liger , Laurent Barroux , Christophe Serre , Christophe Corona , Guillaume Charrier
Date : 2024
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Mountains are particularly vulnerable to climate change, as they are warming at a rate that exceeds the global average, significantly impacting cold-adapted ecosystems. In these environments, soil organic matter (SOM) stocks are often considerably larger than at lower elevations. These stocks are therefore highly susceptible to global warming and the associated risk of greenhouse gas (GHG) (CO₂, CH₄, N₂O) emissions driven by temperature-induced increases in SOM mineralisation. In order to quantify these emissions and the change of mineralisation rates under warming, it is necessary to gain an understanding of the annual mineralisation balance. We investigated how warming impacts the duration and intensity of mineralisation in different seasons. The main aim of this study is to quantify alpine SOM mineralisation rates and GHG production under a range of seasonal conditions, including those associated with warming. An in vitro approach was employed to expose alpine topsoils (0–10 cm) to the conditions of key seasonal periods: snow cover, growing season and rainfall/snowmelt. This was achieved by experimentally varying temperature and inflow of precipitation water. Additionally, the soil samples were subjected to a temperature increase of 4°C. The short-term responses of carbon (C), nitrogen (N) and phosphorus (P) mineralisation and GHG production were monitored. The results demonstrated that alpine soil respiration rates exhibited a twofold increase with a 4°C warming, while the relative proportion of labile SOM demonstrated a decline with rising temperatures. Water saturation from simulated rain and snowmelt played a crucial role in organic matter mineralisation and increased the mineralisation of carbon (+12% to +53%), nitrogen (+20% to +80% of net ammonification) and phosphorus (+50% of net phosphate production). This suggests that nutrients present in the snowpack or the rain were added to the soil. In contrast, soil–water saturation decreased net nitrate production by between 10% and 90%. The results of this study highlight the potential for alpine soil warming to release labile SOM and demonstrate the influence of the snow regime on nutrient and carbon fluxes.
Auteurs, date et publication :
Auteurs Nicolas Bonfanti , Jean-Christophe Clement , Annie Millery-Vigues , Tamara Münkemüller , Yves Perrette , Jérôme Poulenard
Publication : European Journal of Soil Science
Date : 2026
Volume : 76
Issue : 1
Pages : e70050
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Aim Land surface models (LSMs) currently represent each plant functional type (PFT) as an average phenotype, characterised by a set of fixed parameters. This rigid and constant representation is a limit in understanding the dynamics of highly diverse ecosystems, such as permanent grasslands, and their response to global change. Location France. Time Period 2001–2019. Major Taxa Grassland plant species. Methods We incorporated spatially explicit trait variability at the France scale in the ORCHIDEE land surface model to assess how the net primary productivity (NPP) will spatially vary over the years. More precisely, we focused on three key functional traits that govern the NPP of grassland ecosystems: specific leaf area (SLA) and leaf nitrogen content (LNC), as measured traits, and leaf lifespan (LLS) as an estimated trait. Community-weighted means (CWM) were implemented in various combinations with prescribed and spatially varying traits. We compared the outcomes of each NPP simulation to remotely sensed proxies of productivity by using the MODIS satellite-driven NPP products. Results The sensitivity of NPP to traits depends on climate conditions, such as temperature and water limitation. Considering trait variability decreases the NPP in the most productive regions (plains) and increases the NPP in the less productive regions (mountains) compared to the case with constant trait values. This leads to a more homogenous NPP across France. Compared to the observed MODIS NPP and FLUXCOM GPP, the simulation using varying traits improves the spatial NPP and GPP variations in several regions and most climate conditions. Main Conclusions Based on the existing trait data, we revealed that incorporating the CWM of traits in an LSM such as ORCHIDEE can be effectively performed. Improving the modelling and predictions by considering the relationships between biodiversity, functional biogeography, and ecosystem functioning is essential in current and future ecological research.
Auteurs, date et publication :
Auteurs Sara Chebbo , Cyrille Violle , Lucie Mahaut , Jens Kattge , Marc Peaucelle , Philippe Choler , Nicolas Viovy
Publication : Journal of Biogeography
Date : 2026
Volume : n/a
Issue : n/a
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Photosynthesis, electron transport to carbon assimilation, photorespiration and alternative electron transport, light absorption of the two photosystems, antioxidative protection and pigment contents were investigated in S. alpina leaves. S. alpina is an alpine snow-bed plant which can be found with green leaves after snowmelt. At least 24% of the leaves were formed at the beginning of the vegetation period in the previous year and survived two consecutive vegetation periods under contrasting environmental conditions. In leaves still covered by snow (SNOW), the parameters of antioxidative protection and carbon assimilation were lower than in leaves from the previous vegetation period (NEW) or several weeks after snowmelt (OLD). Directly after snowmelt, antioxidative protection was strongly but transitionally increased. The senescence of leaves did not depend on antioxidative scavenging capacity. Lower carbon assimilation was not related to increases in alternative electron flow (ETRalt) in SNOW leaves. In the second vegetation period, light absorption by PSII decreases in favour of PSI in OLD leaves. This allows OLD leaves to keep the electron transport chain more oxidised and to support photorespiration with increased ATP synthesis by cyclic electron transport around PSI. This study describes how the leaves of a unique plant can cope with contrasting environmental conditions.
Auteurs, date et publication :
Auteurs Peter Streb , Philippine Dubertrand , Gabriel Cornic , Kamel Soudani , Giovanni Finazzi
Publication : Physiologia Plantarum
Date : 2026
Volume : 177
Issue : 1
Pages : e70045
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Mountain regions face substantial challenges and opportunities arising from global change. The capacity of mountain regions for (systemic) innovation will be determinant to the success of system transformations envisioned by social actors of mountain communities. By analysing the social networks of two regions in the Alps and relating them to desired future visions of sustainable regional development, we provide insights about innovative capacities in mountain regions and propose how to strengthen these capacities in order to support regional transformations. In particular, we analyse innovation systems’ collaboration networks to evaluate the innovative capacity of communities, co-construct visions with mountain stakeholders, and assess innovation requirements to meet these visions. Accordingly, we propose changes to the collaboration networks for addressing regional innovation system (RIS) capacities to help achieve visions through systemic innovation. Our analysis furthers the understanding on the type and magnitude of regional innovation system changes required to more effectively address desired transformative visions in mountain regions. We close by discussing implications of our approach for the assessment of innovative capacity and the transformation of mountain regions.
Auteurs, date et publication :
Auteurs Victor Blanco , Tobias Luthe , Enora Bruley , Adrienne Grêt-Regamey
Publication : Regional Environmental Change
Date : 2025
Volume : 23
Issue : 3
Pages : 102
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Sanguina nivaloides is the main alga forming red snowfields in high mountains and Polar Regions. It is non-cultivable. Analysis of environmental samples by X-ray tomography, focused-ion-beam scanning-electron-microscopy, physicochemical and physiological characterization reveal adaptive traits accounting for algal capacity to reside in snow. Cysts populate liquid water at the periphery of ice, are photosynthetically active, can survive for months, and are sensitive to freezing. They harbor a wrinkled plasma membrane expanding the interface with environment. Ionomic analysis supports a cell efflux of K+, and assimilation of phosphorus. Glycerolipidomic analysis confirms a phosphate limitation. The chloroplast contains thylakoids oriented in all directions, fixes carbon in a central pyrenoid and produces starch in peripheral protuberances. Analysis of cells kept in the dark shows that starch is a short-term carbon storage. The biogenesis of cytosolic droplets shows that they are loaded with triacylglycerol and carotenoids for long-term carbon storage and protection against oxidative stress.
Auteurs, date et publication :
Auteurs Jade A. Ezzedine , Clarisse Uwizeye , Grégory Si Larbi , Gaelle Villain , Mathilde Louwagie , Marion Schilling , Pascal Hagenmuller , Benoît Gallet , Adeline Stewart , Dimitris Petroutsos , Fabienne Devime , Pascal Salze , Lucie Liger , Juliette Jouhet , Marie Dumont , Stéphane Ravanel , Alberto Amato , Jean-Gabriel Valay , Pierre-Henri Jouneau , Denis Falconet
Publication : Nature Communications
Date : 2023
Volume : 14
Issue : 1
Pages : 7500
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Flowering phenology is important in the adaptation of many plants to their local environment, but its adaptive value has not been extensively studied in herbaceous perennials. We used Arabis alpina as a model system to determine the importance of flowering phenology to fitness of a herbaceous perennial with a wide geographical range. Individual plants representative of local genetic diversity (accessions) were collected across Europe, including in Spain, the Alps and Scandinavia. The flowering behaviour of these accessions was documented in controlled conditions, in common-garden experiments at native sites and in situ in natural populations. Accessions from the Alps and Scandinavia varied in whether they required exposure to cold (vernalization) to induce flowering, and in the timing and duration of flowering. By contrast, all Spanish accessions obligately required vernalization and had a short duration of flowering. Using experimental gardens at native sites, we show that an obligate requirement for vernalization increases survival in Spain. Based on our analyses of genetic diversity and flowering behaviour across Europe, we propose that in the model herbaceous perennial A. alpina, an obligate requirement for vernalization, which is correlated with short duration of flowering, is favoured by selection in Spain where the plants experience a long growing season.
Auteurs, date et publication :
Auteurs Jörg Wunder , Andrea Fulgione , Per Toräng , Stefan Wötzel , Michel Herzog , José Ramón Obeso , Yiannis Kourmpetis , Roeland van Ham , Thomas Odong , Marco Bink , Ulla Kemi , Jon Ågren , George Coupland
Publication : Proceedings of the Royal Society B: Biological Sciences
Date : 2023
Volume : 290
Issue : 2011
Pages : 20231401
Catégorie(s)
#CNRS #Lautaret #UGARésumé
The re-assembly of plant communities during climate warming depends on several concurrent processes. Here, we present a novel framework that integrates spatially explicit sampling, plant trait information and a warming experiment to quantify shifts in these assembly processes. By accounting for spatial distance between individuals, our framework allows separation of potential signals of environmental filtering from those of different types of competition. When applied to an elevational transplant experiment in the French Alps, we found common signals of environmental filtering and competition in all communities. Signals of environmental filtering were generally stronger in alpine than in subalpine control communities, and warming reduced this filter. Competition signals depended on treatments and traits: Symmetrical competition was dominant in control and warmed alpine communities, while hierarchical competition was present in subalpine communities. Our study highlights how distance-dependent frameworks can contribute to a better understanding of transient re-assembly dynamics during environmental change.
Auteurs, date et publication :
Auteurs Billur Bektaş , Wilfried Thuiller , Julien Renaud , Maya Guéguen , Irene Calderón-Sanou , Jean-Gabriel Valay , Marie-Pascale Colace , Tamara Münkemüller
Publication : Ecology Letters
Date : 2025
Volume : 26
Issue : 7
Pages : 1119-1131
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Only a few studies have examined responses of grassland functional diversity to management and major environmental gradients, in order to address the question of whether grassland use can promote functional divergence. For five grassland sites in Israel, Portugal, the Czech Republic, Mediterranean France, and the French Alps, where traditional grassland management is being abandoned, we quantified community-weighted means (CWM) and functional divergence (FDvg) for the three Leaf–Height–Seed (LHS) traits, individually and in combination. Responses of CWM and FDvg to land use were analyzed by mixed linear models with aridity, phosphorus, fertility, and the fractions of grasses and annuals as covariates.
Auteurs, date et publication :
Auteurs Sandra Lavorel , Francesco de Bello , Karl Grigulis , Jan Lepš , Eric Garnier , Helena Castro , Jiri Dolezal , Carly Godolets , Fabien Quétier , Aurélie Thébault
Publication : Israel Journal of Ecology & Evolution
Date : 2025
Volume : 57
Issue : 1-2
Pages : 53-72
Catégorie(s)
#CNRS #Lautaret #UGAAuteurs, date et publication :
Auteurs Karl Grigulis , Sandra Lavorel , Ute Krainer , Nicolas Legay , Catherine Baxendale , Maxime Dumont , Eva Kastl , Cindy Arnoldi , Richard D. Bardgett , Franck Poly , Thomas Pommier , Michael Schloter , Ulrike Tappeiner , Michael Bahn , Jean-Christophe Clément , Michael Hutchings
Publication : Journal of Ecology
Date : 2025
Volume : 101
Issue : 1
Pages : 47-57