Résumé
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
Catégorie(s)
#CNRS #Lautaret #UGAAuteurs, date et publication :
Auteurs Juliana Almario , Ganga Jeena , Jörg Wunder , Gregor Langen , Alga Zuccaro , George Coupland , Marcel Bucher
Publication : Proceedings of the National Academy of Sciences
Date : 2017
Volume : 114
Issue : 44
Pages : E9403-E9412
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Across the globe, invasive alien species cause severe environmental changes, altering species composition and ecosystem functions. So far, mountain areas have mostly been spared from large-scale invasions. However, climate change, land-use abandonment, the development of tourism and the increasing ornamental trade will weaken the barriers to invasions in these systems. Understanding how alien species will react and how native communities will influence their success is thus of prime importance in a management perspective. Here, we used a spatially and temporally explicit simulation model to forecast invasion risks in a protected mountain area in the French Alps under future conditions. We combined scenarios of climate change, land-use abandonment and tourism-linked increases in propagule pressure to test if the spread of alien species in the region will increase in the future. We modelled already naturalized alien species and new ornamental plants, accounting for interactions among global change components, and also competition with the native vegetation. Our results show that propagule pressure and climate change will interact to increase overall species richness of both naturalized aliens and new ornamentals, as well as their upper elevational limits and regional range-sizes. Under climate change, woody aliens are predicted to more than double in range-size and herbaceous species to occupy up to 20% of the park area. In contrast, land-use abandonment will open new invasion opportunities for woody aliens, but decrease invasion probability for naturalized and ornamental alien herbs as a consequence of colonization by native trees. This emphasizes the importance of interactions with the native vegetation either for facilitating or potentially for curbing invasions. Overall, our work highlights an additional and previously underestimated threat for the fragile mountain flora of the Alps already facing climate changes, land-use transformations and overexploitation by tourism.
Auteurs, date et publication :
Auteurs Marta Carboni , Maya Guéguen , Ceres Barros , Damien Georges , Isabelle Boulangeat , Rolland Douzet , Stefan Dullinger , Guenther Klonner , Mark van Kleunen , Franz Essl , Oliver Bossdorf , Emily Haeuser , Matthew V. Talluto , Dietmar Moser , Svenja Block , Luisa Conti , Iwona Dullinger , Tamara Münkemüller , Wilfried Thuiller
Publication : Global Change Biology
Date : 2025
Volume : 24
Issue : 1
Pages : e289-e302
Catégorie(s)
#CNRS #Lautaret #UGAAuteurs, date et publication :
Auteurs Thomas Pommier , Amélie A. M. Cantarel , Karl Grigulis , Sandra Lavorel , Nicolas Legay , Catherine Baxendale , Richard D. Bardgett , Michael Bahn , Franck Poly , Jean-Christophe Clément , Marney Isaac
Publication : Journal of Applied Ecology
Date : 2025
Volume : 55
Issue : 1
Pages : 49-58
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Methods: A manipulative experiment tested the reciprocal effects of mowing cessation and mowing resumption for ten years. We analysed floristic composition data following four steps. First, we used the Community Structure Integrity Index (CSII) (Jaunatre et al. 2013) to obtain qualitative and quantitative summaries of taxonomic responses. The second step focused on taxonomic biodiversity using species richness, Simpson and Pielou indices, and on responsive species identified in the first step. Third, we analyzed functional diversity responses using functional groups and community weighted mean (CWM) of vegetative plant traits. Finally, we quantified ecosystem services impacts by estimating fodder quantity and quality using trait-based models.
Results: The mowing manipulation demonstrated the high resilience of P. paniculata grasslands, and revealed reversibility of transitions between mown and unmown states. By reducing the abundance of P. paniculata, the resumption of mowing restored forage quality. Supported by a complementary case study on post-disturbance resowing in hay meadows, this study demonstrates the resilience of mown subalpine grasslands to management change and explores underlying belowground mechanisms of vegetative regeneration and belowground reserves.
Conclusion: Our novel multi-indicator approach provides multi-faceted mechanistic understanding necessary to anticipate impacts of socio-ecological changes and to maintain the multiple benefits of mountain grasslands. Addressing the different facets of biodiversity from abundance data that is systematically collected in impact or monitoring assessment, this approach provides a common framework, widely applicable for different types of restoration or management interventions, across regions and biota.
Auteurs, date et publication :
Auteurs Iris Lochon , Marie-Pascale Colace , Caroline Devaux , Karl Grigulis , Ricarda Rettinger , Sandra Lavorel
Publication : Applied Vegetation Science
Date : 2025
Volume : 21
Issue : 4
Pages : 636-646
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Nitrogen (N) emissions associated with urbanization exacerbate the atmospheric N influx to remote ecosystems – like mountains –, leading to well-documented detrimental effects on ecosystems (e.g., soil acidification, pollution of freshwaters). Here, the importance and fate of N deposition in a watershed was evaluated along a montane to urban gradient, using a multi-isotopic tracers approach (Δ17O, δ15N, δ18O of nitrate, δ2H and δ18O of water). In this setting, the montane streams had higher proportions of atmospheric nitrate compared to urban streams, and exported more atmospheric nitrate on a yearly basis (0.35 vs 0.10 kg-N ha−1 yr−1). In urban areas, nitrate exports were driven by groundwater, whereas in the catchment head nitrate exports were dominated by surface runoff. The main sources of nitrate to the montane streams were microbial nitrification and atmospheric deposition, whereas microbial nitrification and sewage leakage contributed most to urban streams. Based on the measurement of δ15N and δ18O-NO− 3 , biological processes such as denitrification or N assimilation were not predominant in any streams in this study. The observed low δ15N and δ18O range of terrestrial nitrate (i. e., nitrate not coming from atmospheric deposition) in surface water compared to literature suggests that atmospheric deposition may be underestimated as a direct source of N.
Auteurs, date et publication :
Auteurs Ilann Bourgeois , Joel Savarino , Julien Némery , Nicolas Caillon , Sarah Albertin , Franck Delbart , Didier Voisin , Jean-Christophe Clément
Publication : Science of The Total Environment
Date : 2025
Volume : 633
Pages : 329-340