Auteurs, date et publication :
Auteurs Lydie Blottière , Mourad Jaffar-Bandjee , Stéphan Jacquet , Alexis Millot , Florence D. Hulot
Publication : Freshwater Biology
Date : 2025
Volume : 62
Issue : 1
Pages : 161-177
Catégorie(s)
#CNRS #ENS #INRAE #OLARésumé
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 #UGAAuteurs, date et publication :
Auteurs Michael Danger , Béatrice Allard , Mohamad B. Arnous , Jean-François Carrias , Jacques Mériguet , Loïc Ten-Hage , Gérard Lacroix
Publication : Hydrobiologia
Date : 2025
Volume : 679
Issue : 1
Pages : 251-266
Catégorie(s)
#CNRS #ENS #PLANAQUARésumé
Abstract. Continental relative humidity (RH) is a key-climate parameter. However, there is a lack of quantitative RH proxies suitable for climate model-data comparisons. Recently, a combination of climate chamber and natural transect calibrations laid the groundwork for examining the robustness of the triple oxygen isotope composition (δ18O, δ17O) of phytoliths as a new proxy for past changes in RH. However, it was recommended that besides RH, additional factors that may impact δ18O and δ17O of plant water and phytoliths be examined. Here, the effects of leaf anatomy, leaf development stage and day/night alternations are addressed from the growth of the grass species F. arundinacea in climate chambers. Plant water and phytoliths are analyzed in δ18O and δ17O. Silicification patterns are examined using light and scanning electron observation of phytoliths. The isotope data show the increasing contribution of evaporated epidermal water to the bulk leaf water, from sheath to proximal and apical leaf blade. However, despite this isotope heterogeneity, δ18O and δ17O of the bulk leaf water can be predicted by the Craig and Gordon model, in the given experimental conditions (high RH). Regarding phytoliths, their forming water (mainly epidermal) is, as expected, more impacted by evaporation than the bulk leaf water. This discrepancy increases from sheath to proximal and apical blade and can be explained by the steepening of the radial concentration gradient of evaporated water along the leaf. However, we show that because most of silica polymerizes in epidermal long cells of the apical blade of the leaves, the δ18O and δ17O of bulk grass phytoliths should not be impacted by the diversity in grass anatomy. The data additionally show that most of silica polymerizes at the end of the leaf elongation stage and at the transition towards leaf senescence. Thus, climate conditions at that time should be considered when interpreting δ18O and δ17O of phytoliths from the natural environment. At least, no light/dark effect was detected on the δ18O and δ17O signature of plant water and phytoliths of F. arundinacea. However, when day/night alternations are characterized by significant changes in RH, the lowest RH conditions favoring evaporation and silica polymerization should be considered when calibrating the phytolith proxy. This study contributes to the identification of the parameters driving the δ18O and δ17O of bulk grass phytoliths. It additionally brings elements to further understand and model the δ18O and δ17O of grass leaf water, which influences the isotope signal of several processes at the soil/plant/atmosphere interface.
Auteurs, date et publication :
Auteurs Anne Alexandre , Elizabeth Webb , Amaelle Landais , Clément Piel , Sébastien Devidal , Corinne Sonzogni , Martine Couapel , Jean-Charles Mazur , Monique Pierre , Frédéric Prié , Christine Vallet-Coulomb , Jacques Roy
Publication : Biogeosciences Discussions
Date : 2019
Catégorie(s)
#CNRS #Ecotron de MontpellierRésumé
Plants play an important role in carbon and nitrogen fluxes in the
environment. Plants remove carbon from the atmosphere through
photosynthesis and deposit a fraction of this carbon into the soil as a
result of root exudation and senescence, contributing to soil formation.
Additionally, plants can facilitate sequestration of CO2 from the
atmosphere in inorganic form during the process of mineral weathering.
With increasing temperatures and levels of CO2 in the atmosphere, it is
unknown what effect these changes will have on plant growth and
weathering of silicate rocks, and by extension on carbon accumulation in
the soils. To identify climate change effects on C and N fluxes, a
controlled study was conducted at Ecotron Ile-de-France utilizing
mesocosms maintained at elevated and ambient CO2 concentration and
temperature with four different vegetation treatments: control, alfalfa,
velvet mesquite, and green sprangletop. Each experiment lasted for 4
months with monthly rainfall events using deionized water. After each
rain, soil solution and drainage were collected and analyzed for major
and trace elements, as well as anions, nitrogen, and organic and
inorganic carbon. CO2 concentrations in the soil air were monitored as
well. At the end of this study, soil samples were collected from each
mesocosm at four different depths and then analyzed for organic carbon,
inorganic carbon, and total nitrogen. Accumulation of organic and
inorganic carbon and nitrogen with clear differences with depth was
observed in all mesocosms. Elevated CO2 in the atmosphere influenced C
accumulation in the soils, while the type of vegetation significantly
affected concentrations of nitrogen and organic carbon in soil and
solution. This indicates that climate change would affect carbon and
nitrogen fluxes in the soils causing feedbacks to the atmospheric CO2.
Auteurs, date et publication :
Auteurs R. Hingley , S. Juarez , K. Dontsova , E. Hunt , J. F. Le Galliard , S. Chollet , A. Cros , M. Llavata , F. Massol , P. Barré , A. Gelabert , D. Daval , P. A. A. Troch , G. Barron-Gafford , J. L. M. Van Haren , R. Ferrière
Date : 2016
Volume : 53
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSRésumé
Jumping is an important form of locomotion, and animals employ a variety of mechanisms to increase jump performance. While jumping is common in insects generally, the ability to jump is rare among ants. An exception is the Neotropical ant Gigantiops destructor (Fabricius 1804) which is well known for jumping to capture prey or escape threats. Notably, this ant begins a jump by rotating its abdomen forward as it takes off from the ground. We tested the hypotheses that abdominal rotation is used to either provide thrust during takeoff or to stabilize rotational momentum during the initial airborne phase of the jump. We used high speed videography to characterize jumping performance of G. destructor workers jumping between two platforms. We then anesthetized the ants and used glue to prevent their abdomens from rotating during subsequent jumps, again characterizing jump performance after restraining the abdomen in this manner. Our results support the hypothesis that abdominal rotation provides additional thrust as the maximum distance, maximum height, and takeoff velocity of jumps were reduced by restricting the movement of the abdomen compared with the jumps of unmanipulated and control treatment ants. In contrast, the rotational stability of the ants while airborne did not appear to be affected. Changes in leg movements of restrained ants while airborne suggest that stability may be retained by using the legs to compensate for changes in the distribution of mass during jumps. This hypothesis warrants investigation in future studies on the jump kinematics of ants or other insects.
Auteurs, date et publication :
Auteurs Dajia Ye , Joshua C Gibson , Andrew V Suarez
Publication : Integrative Organismal Biology
Date : 2020
Volume : 2
Issue : obz033
Catégorie(s)
#CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Amélie Saunier , Elena Ormeño , Christophe Boissard , Henri Wortham , Brice Temime-Roussel , Caroline Lecareux , Alexandre Armengaud , Catherine Fernandez
Publication : Atmospheric Chemistry and Physics
Date : 2017
Volume : 17
Issue : 12
Pages : 7555-7566
Catégorie(s)
#CNRS #FORET O3HPAuteurs, date et publication :
Auteurs Luc Allard , Manon Popée , Régis Vigouroux , Sébastien Brosse
Publication : Aquatic sciences
Date : 2025
Volume : 78
Issue : 2
Pages : 315-325
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Fungal communities in the root endosphere are heterogeneous at fine scale. The passenger hypothesis assumes that this heterogeneity is driven by host plant distribution. Plant composition and host plant configuration should then influence root fungal assemblages. We used a large-scale experimental design of 25 mixtures of grassland plants. We sampled Brachypodium pinnatum in each mesocosm, and used amplicon mass-sequencing to analyze the endospheric mycobiota. We used plant distribution maps to assess plant species richness and evenness (heterogeneity of composition), and patch size and the degree of isolation of B. pinnatum (heterogeneity of configuration) on fungal community assembly. The Glomeromycotina community in B. pinnatum roots was not related to either floristic heterogeneity or productivity. For Ascomycota, the composition of operational taxonomic units (OTUs) was driven by plant evenness while OTU richness decreased with plant richness. For Basidiomycota, richness increased with host plant aggregation and connectivity. Plant productivity influenced Ascomycota, inducing a shift in OTU composition and decreasing evenness. Plant heterogeneity modified root mycobiota, with potential direct (i.e. host preference) and indirect (i.e. adaptations to abiotic conditions driven by plant occurrence over time) effects. Plant communities can be envisioned as microlandscapes consisting of a variety of fungal niches.
Auteurs, date et publication :
Auteurs Cendrine Mony , Philomène Brunellière , Nathan Vannier , Anne-Kristel Bittebiere , Philippe Vandenkoornhuyse
Publication : New Phytologist
Date : 2025
Volume : 225
Issue : 4
Pages : 1777-1787
Catégorie(s)
#CNRS #EcoGenO #Université de RennesRésumé
• Introduction Millions of hectares of Quercus ilex forests dominate disturbed landscapes in the western part of the Mediterranean basin. Although these forests are very widespread, little is known about the composition and structure of their associated ectomycorrhizal fungal communities.• Results and discussion We examined seasonal patterns in ectomycorrhizal communities and their response to increased drought using a rainfall exclusion experiment established in a Q. ilex coppice since 2003. Ectomycorrhizae were sampled four times in 2007–2009. By sequencing fungal ITS, we identified 129 species in 1,147 sequenced ectomycorrhizal root tips. The fungal community in the surface organic horizon was well described by the logseries theoretical model, with 47.9% of singleton species. The composition of the community was strongly dominated by Basidiomycetes, with three families (Thelephoraceae, Russulaceae and Cortinariaceae) accounting for 72.9% of the root tips. Relative abundance of Russulaceae and Thelephoraceae showed pronounced seasonal shifts. Experimental reduction of rainfall resulted in significant shifts in community composition and seasonal fluctuations but had no effect on global richness of the community.• Conclusions Together, these results suggest that the predicted rainfall reduction in this region due to climate change will lead to shifts in species composition in ectomycorrhizal communities.
Auteurs, date et publication :
Auteurs Franck Richard , Melanie Roy , Oula Shahin , Christopher Sthultz , Myriam Duchemin , Richard Joffre , Marc-André Selosse
Publication : Annals of Forest Science
Date : 2011
Volume : 68
Issue : 1
Pages : 57-68