Résumé
Functional trait differences among species are increasingly used to infer the effects of biotic and abiotic processes on species coexistence. Commonly, the trait diversity observed within communities is compared to patterns simulated in randomly generated communities based on sampling within a region. The resulting patterns of trait convergence and divergence are assumed to reveal abiotic and biotic processes, respectively. However, biotic processes such as competition can produce both trait divergence and convergence, through either excluding similar species (niche differences, divergence) or excluding dissimilar species (weaker competitor exclusion, convergence). Hence, separating biotic and abiotic processes that can produce identical patterns of trait diversity, or even patterns that neutralize each other, is not feasible with previous methods. We propose an operational framework in which the functional trait dissimilarity within communities (FDcomm) is compared to the corresponding trait dissimilarity expected from the species pool (i.e., functional species pool diversity, FDpool). FDpool includes the set of potential species for a site delimited by the operating environmental and dispersal limitation filters. By applying these filters, the resulting pattern of trait diversity is consistent with biotic processes, i.e., trait divergence (FDcomm . FDpool) indicates niche differentiation, while trait convergence (FDcomm , FDpool) indicates weaker competitor exclusion. To illustrate this framework, with its potential application and constraints, we analyzed both simulated and field data. The functional species pool framework more consistently detected the simulated trait diversity patterns than previous approaches. In the field, using data from plant communities of typical Northern European habitats in Estonia, we found that both niche-based and weaker competitor exclusion influenced community assembly, depending on the traits and community considered. In both simulated and field data, we demonstrated that only by estimating the species pool of a site is it possible to differentiate the patterns of trait dissimilarity produced by operating biotic processes. The framework, which can be applied with both functional and phylogenetic diversity, enables a reinterpretation of community assembly processes. Solving the challenge of defining an appropriate reference species pool for a site can provide a better understanding of community assembly.
Auteurs, date et publication :
Auteurs Francesco de Bello , Jodi N. Price , Tamara Münkemüller , Jaan Liira , Martin Zobel , Wilfried Thuiller , Pille Gerhold , Lars Götzenberger , Sébastien Lavergne , Jan Lepš , Kristjan Zobel , Meelis Pärtel
Publication : Ecology
Date : 2025
Volume : 93
Issue : 10
Pages : 2263-2273
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Evergreen plants growing at high latitudes or high elevations may experience freezing events in their photosynthetic tissues. Freezing events can have physical and physiological effects on the leaves which alter leaf optical properties affecting remote and proximal sensing parameters. We froze leaves of six alpine plant species (Soldanella alpina, Ranunculus kuepferi, Luzula nutans, Gentiana acaulis, Geum montanum, and Centaurea uniflora) and three evergreen forest understorey species (Hepatica nobilis, Fragaria vesca and Oxalis acetosella), and assessed their spectral transmittance and optically measured pigments, as well as photochemical efficiency of photosystem II (PSII) as an indicator of freezing damage. Upon freezing, leaves of all the species transmitted more photosynthetically active radiation (PAR) and some species had increased ultraviolet-A (UV-A) transmittance. These differences were less pronounced in alpine than in understorey species, which may be related to higher chlorophyll degradation, visible as reduced leaf chlorophyll content upon freezing in the latter species. Among these understorey forbs, the thin leaves of O. acetosella displayed the largest reduction in chlorophyll (−79%). This study provides insights into how freezing changes the leaf optical properties of wild plants which could be used to set a baseline for upscaling optical reflectance data from remote sensing. Changes in leaf transmittance may also serve to indicate photosynthetic sufficiency and physiological tolerance of freezing events, but experimental research is required to establish this functional association.
Auteurs, date et publication :
Auteurs Twinkle Solanki , José Ignacio García Plazaola , T. Matthew Robson , Beatriz Fernández Marín
Publication : Photochemical & Photobiological Sciences
Date : 2022
Issue : 21
Pages : 997-1009
Catégorie(s)
#CNRS #Lautaret #UGARésumé
The significance of foliar uptake of nitrogen (N) compounds in natural conditions is not well understood, despite growing evidence of its importance to plant nutrition. In subalpine meadows, N-limitation fosters the dominance of specific subalpine plant species, which in turn ensure the provision of essential ecosystems services. Understanding how these plants absorb N and from which sources is important to predict ecological consequences of increasing N deposition. Here, we investigate the sources of N to plants from subalpine meadows with distinct land-use history in the French Alps, using the triple isotopes (Δ17 O, δ18 O, and δ15 N) of plant tissue nitrate (NO3- ). We use this approach to evaluate the significance of foliar uptake of atmospheric NO3- (NO3-atm ). The foliar uptake of NO3-atm accounted for 4-16% of the leaf NO3- content, and contributed more to the leaf NO3- pool after peak biomass. Additionally, the gradual 15 N enrichment of NO3- from the soil to the leaves reflected the contribution of NO3-atm assimilation to plants' metabolism. The present study confirms that foliar uptake is a potentially important pathway for NO3-atm into subalpine plants. This is of major significance as N emissions (and deposition) are predicted to increase globally in the future. This article is protected by copyright. All rights reserved.
Auteurs, date et publication :
Auteurs Ilann Bourgeois , Jean-Christophe Clément , Nicolas Caillon , Joël Savarino
Publication : New Phytologist
Date : 2019
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Land use has an effect on seed strategies. It is debated, however, whether disturbances such as mowing select for one dominant regeneration strategy (e.g. ruderals) or allows for more species with diverse recruitment strategies to establish. We tested if there is a filtering of seed traits in subalpine grasslands and what is the effect of mowing on community mean seed traits and their diversity. We measured seed mass and seed number of most species from subalpine grasslands in the French Alps, in an experiment consisting of short- and long-term mowing. We calculated for each treatment average seed mass and number as well as functional divergence. Mowing had no effect either on mean seed trait values or trait diversity, but rather reversed the effect of moisture on seed traits. Most importantly, besides soil moisture, communities followed a continuum from grasslands dominated by species with heavy seeds to grasslands with high divergence in seed mass. These results suggest the existence of an axis of functional divergence–convergence for seed mass in response to factors other than disturbance, though we were not able to identify which. Functional space (i.e. available niches along seed trait dimensions) exists for species with varied strategies in some of the communities, as opposed to others where species with heavy seed masses prevail. Reproductive strategies and the availability of diverse regeneration niches may determine a more important assembly rule of plant species in subalpine communities than previously considered.
Auteurs, date et publication :
Auteurs Flore Viard-Crétat , Francesco de Bello , Ove Eriksson , Marie-Pascale Colace , Sandra Lavorel
Publication : Basic and Applied Ecology
Date : 2025
Volume : 12
Issue : 5
Pages : 423-431
Catégorie(s)
#CNRS #Lautaret #UGAAuteurs, date et publication :
Auteurs Ceres Barros , Maya Guéguen , Rolland Douzet , Marta Carboni , Isabelle Boulangeat , Niklaus E. Zimmermann , Tamara Münkemüller , Wilfried Thuiller , Akira Mori
Publication : Journal of Applied Ecology
Date : 2025
Volume : 54
Issue : 1
Pages : 39-50
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Cushion-forming species occur in all cold and dry environments worldwide, where they play important engineering roles. Understanding the origins of cushion plants may thus provide insights into the evolutionary assembly of biomes under extreme climatic conditions. Here we investigate the evolutionary and biogeographic history of cushions in Angiosperms based on a global checklist of all cushion plants, along with phylogenetic, climatic, and biogeographic information. Our aim is to measure the frequency of this evolutionary convergence and to identify its historic, environmental, and biogeographic drivers. We show that cushions appeared at least 115 times in Angiosperms and that they mainly belong to families that occupy the coldest and driest environments on Earth. We found that cushions have intensively diversified in the Himalayas, the Andes, or New Zealand, while other regions like Patagonia have probably been hubs enabling cushion species to migrate between different alpine regions. We conclude that the cushion life form is a remarkable example of convergent key innovation, which has favored the colonization of cold and dry habitats.
Auteurs, date et publication :
Auteurs Florian C. Boucher , Sébastien Lavergne , Mireille Basile , Philippe Choler , Serge Aubert
Publication : Perspectives in Plant Ecology, Evolution and Systematics
Date : 2025
Volume : 20
Pages : 22-31
Catégorie(s)
#CNRS #Lautaret #UGARésumé
In this study, we propose a methodology to estimate the spatial distribution of destabilizing rock glaciers, with a focus on the French Alps. We mapped geomorphological features that can be typically found in cases of rock glacier destabilization (e.g. crevasses and scarps) using orthoimages taken from 2000 to 2013. A destabilization rating was assigned by taking into account the evolution of these mapped destabilization geomorphological features and by observing the surface deformation patterns of the rock glacier, also using the available orthoimages. This destabilization rating then served as input to model the occurrence of rock glacier destabilization in relation to terrain attributes and to spatially predict the susceptibility to destabilization at a regional scale. Significant evidence of destabilization could be observed in 46 rock glaciers, i.e. 10 % of the total active rock glaciers in the region. Based on our susceptibility model of destabilization occurrence, it was found that this phenomenon is more likely to occur in elevations around the 0 ◦C isotherm (2700–2900 m a.s.l.), on north-facing slopes, steep terrain (25 to 30◦) and flat to slightly convex topographies. Model performance was good (AUROC = 0.76), and the susceptibility map also performed well at reproducing observable patterns of destabilization. About 3 km2 of creeping permafrost, or 10 % of the surface occupied by active rock glaciers, had a high susceptibility to destabilization. Considering we observed that only half of these areas of creep are currently showing destabilization evidence, we suspect there is a high potential for future rock glacier destabilization within the French Alps.
Auteurs, date et publication :
Auteurs Marco Marcer , Charlie Serrano , Alexander Brenning , Xavier Bodin , Jason Goetz , Philippe Schoeneich
Publication : The Cryosphere
Date : 2019
Volume : 13
Issue : 1
Pages : 141-155
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Soldanella alpina differing in leaf epidermal UV-A absorbance (DEA375), as measured with the Dualex, was investigated as a model alpine plant for the flavonoid (Flav) composition and concentration and for anatomical and pigment characteristics. In sun leaves, twenty-three flavones were characterised by their mass formula, their maximum absorption, their glycosylation, their methylation and dehydroxylation pattern. The flavones belonged to four subfamilies (tetra-hydroxy-flavones, penta-hydroxy-flavones, penta-hydroxy-methyl-flavones and tri-hydroxy-di-methoxy-flavones), abundant in sun and shade leaves. Their concentration was estimated by their absorption at 350 nm after HPLC separation. Sun leaves contained relatively higher contents of penta-hydroxy-methyl-flavones and shade leaves higher contents of tetra-hydroxy-flavones. The flavones were present mainly in vacuoles, all over the leaf. After shade-sun transfer, the content of most flavones increased, irrespective of the presence or absence of UV radiation. Highly significant correlations with the log-transformed DEA375 suggest that DEA375 can be readily applied to predict the flavone content of S. alpina leaves. Shade-sun transfer of leaves decreased the hydroxycinnamic acid (HCA) content, the mass-based chlorophyll (Chl) a+b content and the Chl/Carotenoid (Car) ratio but increased DEA375, and the Car content. Together with previously reported anatomical characteristics all these parameters correlated significantly with the DEA375. The Flav content is therefore correlated to most of the structural characteristics of leaf acclimation to light and this can be probed in situ by DEA375.
Auteurs, date et publication :
Auteurs Luc P. R. Bidel , Sylvie Meyer , Anne-Claire Talhouët , Xavier Baudin , Caroline Daniel , Guillaume Cazals , Peter Streb
Publication : Plant Physiology and Biochemistry
Date : 2020
Volume : 151
Pages : 10-20
Catégorie(s)
#CNRS #Lautaret #UGAAuteurs, date et publication :
Auteurs Andrea E. Berardi , Peter D. Fields , Jessica L. Abbate , Douglas R. Taylor
Publication : American Journal of Botany
Date : 2025
Volume : 103
Issue : 8
Pages : 1508-1523
Catégorie(s)
#CNRS #Lautaret #UGAAuteurs, date et publication :
Auteurs Jessica L. Abbate , Janis Antonovics
Publication : Oikos
Date : 2025
Volume : 123
Issue : 9
Pages : 1126-1136