Résumé
In the high Arctic, thermal bridging through frozen shrub branches has been demonstrated to cool the ground by up to 4°C during cold spells, affecting snow metamorphism and soil carbon and nutrients. In alpine conditions, the thermal conductivity contrast between shrub branches and snow is much less than in the Arctic, so that the importance of thermal bridging is uncertain. We explore this effect by monitoring ground temperature and liquid water content under green alders and under nearby alpine tundra in the Alps. During a January 2022 cold spell, the ground temperature at 5 cm depth under alders is 1.3°C colder than under alpine tundra. Ground water freezing under alders is complete, while water remains liquid under tundra. Finite element simulations reproduce the observed temperature difference between both sites, showing that thermal bridging does affect ground temperature also under Alpine conditions.
Auteurs, date et publication :
Auteurs Florent Domine , Kevin Fourteau , Philippe Choler
Publication : Geophysical Research Letters
Date : 2023
Volume : 50
Issue : 24
Pages : e2023GL105100
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Introduction
In contrast to the dynamics observed in plant/pathogen interactions, endophytic fungi have the capacity to establish enduring associations within their hosts, leading to the development of a mutually beneficial relationship that relies on specialized chemical interactions. Research indicates that the presence of endophytic fungi has the ability to significantly modify the chemical makeup of the host organism. Our hypothesis proposes the existence of a reciprocal exchange of chemical signals between plants and fungi, facilitated by specialized chemical processes that could potentially manifest within the tissues of the host. This research aimed to precisely quantify the portion of the cumulative fungal endophytic community's metabolome detectable within host leaves, and tentatively evaluate its relevance to the host-endophyte interplay. The understory palm Astrocaryum sciophilum (Miq.) Pulle was used as a interesting host plant because of its notable resilience and prolonged life cycle, in a tropical ecosystem.
Method
Using advanced metabolome characterization, including UHPLC-HRMS/MS and molecular networking, the study explored enriched metabolomes of both host leaves and 15 endophytic fungi. The intention was to capture a metabolomic "snapshot" of both host and endophytic community, to achieve a thorough and detailed analysis.
Results and discussion
This approach yielded an extended MS-based molecular network, integrating diverse metadata for identifying host- and endophyte-derived metabolites. The exploration of such data (>24000 features in positive ionization mode) enabled effective metabolome comparison, yielding insights into cultivable endophyte chemodiversity and occurrence of common metabolites between the holobiont and its fungal communities. Surprisingly, a minor subset of features overlapped between host leaf and fungal samples despite significant plant metabolome enrichment. This indicated that fungal metabolic signatures produced in vitro remain sparingly detectable in the leaf. Several classes of primary metabolites were possibly shared. Specific fungal metabolites and/or compounds of their chemical classes were only occasionally discernible in the leaf, highlighting endophytes partial contribution to the overall holobiont metabolome. To our knowledge, the metabolomic study of a plant host and its microbiome has rarely been performed in such a comprehensive manner. The general analytical strategy proposed in this paper seems well-adapted for any study in the field of microbial- or microbiome-related MS and can be applied to most host-microbe interactions.
Auteurs, date et publication :
Auteurs Leonie Pellissier , Arnaud Gaudry , Salomé Vilette , Nicole Lecoultre , Adriano Rutz , Pierre-Marie Allard , Laurence Marcourt , Emerson Ferreira Queiroz , Jérôme Chave , Véronique Eparvier , Didier Stien , Katia Gindro , Jean-Luc Wolfender
Publication : Frontiers in Plant Science
Date : 2023
Volume : 14
Pages : 1278745
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Earthworms can stimulate microbial activity and hence greenhouse gas (GHG) emissions from soils. However, the extent of this effect in the presence of plants and soil moisture fluctuations, which are influenced by earthworm burrowing activity, remains uncertain. Here, we report the effects of earthworms (without, anecic, endogeic, both) and plants (with, without) on GHG (CO2, N2O) emissions in a 3-month greenhouse mesocosm experiment simulating a simplified agricultural context. The mesocosms allowed for water drainage at the bottom to account for the earthworm engineering effect on water flow during two drying-wetting cycles. N2O cumulative emissions were 34.6% and 44.8% lower when both earthworm species and only endogeic species were present, respectively, and 19.8% lower in the presence of plants. The presence of the endogeic species alone or in combination with the anecic species slightly reduced CO2 emissions by 5.9% and 11.4%, respectively, and the presence of plants increased emissions by 6%. Earthworms, plants and soil water content interactively affected weekly N2O emissions, an effect controlled by increased soil dryness due to drainage via earthworm burrows and mesocosm evapotranspiration. Soil macroporosity (measured by X-ray tomography) was affected by earthworm species-specific burrowing activity. Both GHG emissions decreased with topsoil macropore volume, presumably due to reduced moisture and microbial activity. N2O emissions decreased with macropore volume in the deepest layer, likely due to the presence of fewer anaerobic microsites. Our results indicate that, under experimental conditions allowing for plant and earthworm engineering effects on soil moisture, earthworms do not increase GHG emissions, and endogeic earthworms may even reduce N2O emissions.
Auteurs, date et publication :
Auteurs Pierre Ganault , Johanne Nahmani , Yvan Capowiez , Nathalie Fromin , Ammar Shihan , Isabelle Bertrand , Bruno Buatois , Alexandru Milcu
Publication : PloS One
Date : 2025
Volume : 19
Issue : 2
Pages : e0289859
Catégorie(s)
#ANR-Citation #CNRS #Ecotron de MontpellierRésumé
Landscape heterogeneity is known as a major factor of community structure and composition. Whether this effect of the landscape extends at different scales and particularly at the relevant scale for microorganisms remained to be determined. We used th
Auteurs, date et publication :
Auteurs Joey Allen , Marion Sire , Nadege Belouard , Caroline Gorzerino , Marie-Agnes Coutellec , Cendrine Mony , Alexandrine Pannard , Christophe Piscart
Date : 2025
Catégorie(s)
#CNRS #EcoGenO #Université de RennesAuteurs, date et publication :
Auteurs David Dumoulin Kervran
Publication : Zilsel
Date : 2025
Volume : N° 14
Issue : 1
Pages : 293-311
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Fine roots mediate plant nutrient acquisition and growth. Depending on soil nutrient availability, plants can regulate fine root biomass and morphological traits to optimise nutrient acquisition. Little is known, however, about the importance of these parameters influencing forest functioning. In this study, we measured root responses to nutrient additions to gain a mechanistic understanding of plant adaptations to nutrient limitation in two tropical forests in French Guiana, differing twofold in their soil nutrient statuses. We analysed the responses of root biomass, mean root diameter (RD), specific root length (SRL), specific root area (SRA), root tissue density (RTD) and carbon (C), nitrogen (N) and phosphorus (P) concentrations in roots down to 15 cm soil depth after three years of N and P additions. At the lower-fertility site Paracou, no changes in root biomass or morphological traits were detected with either N or P addition, although P concentrations in roots increased with P addition. In the higher fertility site, Nouragues, root biomass and P concentrations in roots increased with P addition, with no changes in morphological traits. In contrast, N addition shifted root traits from acquisitive to more conservative by increasing RTD. A significant interaction between N and P in Nouragues pointed to stronger responses to P addition in the absence of N. Our results suggest that the magnitude and direction of root biomass and trait expression were regulated by soil fertility, corroborated by the response to N or P additions. At low fertility sites, we found lower plasticity in root trait expression compared to more fertile conditions, where N and P additions caused stronger and antagonistic responses. Identifying the exact role of mechanisms affecting root nutrient uptake in Amazon forests growing in different soils will be crucial to foresee if and how rapid global changes can affect their carbon allocation.
Auteurs, date et publication :
Auteurs Laynara F. Lugli , Lucia Fuchslueger , Helena Vallicrosa , Leandro Van Langenhove , Christian Ranits , Pere Roc Fernandez Garberi , Lore Verryckt , Oriol Grau , Laëtitia Bréchet , Guille Peguero , Joan Llusia , Romà Ogaya , Laura Marquez , Miguel Portillo-Estrada , Irene Ramirez-Rojas , Elodie Courtois , Clement Stahl , Jordi Sardans , Josep Penuelas , Erik Verbruggen
Publication : Oikos
Date : 2025
Volume : 2024
Issue : 4
Pages : e10412
Catégorie(s)
#ANR-Citation #CNRS #FORET Nouragues #FORET ParacouRésumé
An important question in evolutionary biology is to identify the mechanisms that control the number of reproductives in social groups. Ants are appropriate models to address this question because of the variety of their social structures both within and between species, making this taxon suitable for initiating comparative studies to examine the drivers of this diversity. In this study, we developed a comparative approach between populations of the ponerine ant Odontomachus hastatus from Brazil and French Guiana. In Brazil, monogynous and polygynous colonies coexist in the same populations, whereas only monogynous colonies are present in French Guiana. We combined ecological, behavioural and chemical analyses to identify the factors associated with the expression of this social polymorphism. In Brazil, nest densities were higher than in French Guiana, but nesting sites were available in large quantities in both areas, indicating that habitat saturation is probably not the cause of social polymorphism. We did not detect any difference in queen size, regardless of the social structure of the colonies, suggesting that dispersal strategies may be similar between monogynous and polygynous populations. We found no influence of social structure on aggression intensity in dyadic encounters between workers. Last, we showed that the level of aggression increased with both geographical and chemical distance, but we did not find any difference in cuticular profiles between monogynous and polygynous colonies. Overall, the determinism of social polymorphism in O. hastatus still eludes us and calls for further field experiments coupled with genetic approaches.
Auteurs, date et publication :
Auteurs C. Bottcher , K. Berthelot , A. Bernadou , J. Orivel , V. Fourcassié , P. S. Oliveira , R. Jeanson
Publication : Insectes Sociaux
Date : 2025
Volume : 71
Issue : 1
Pages : 61-73
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Mountain shrublands are widespread habitats of the European Alps. Shrub encroachment into above treeline grazed lands profoundly modifies biodiversity and ecosystem functioning. Yet, mountain shrublands remain overlooked in vegetation distribution modeling because it is difficult to distinguish them from productive grasslands. Here, we used the pigment-sensitive spectral indices based on Sentinel-2 bands within a specific phenological window, to produce a high-resolution distribution map of mountain shrublands in the French Alps. We evaluated the performance of our classification using a large dataset of vegetation plots and found that our model is highly sensitive to Ericaceous species which constitute most of the dense alpine shrublands in the French Alps. Our analysis of topoclimatic and land use factors limiting the shrubland distribution at regional scale found that, consistent with the ecophysiology of shrubs, expansion is limited by a combination of water deficit and temperature. We discussed the past and current land-use implications in the observed distribution and put forward hypotheses combining climate and land-use trajectories. Our work provides a baseline for monitoring mountain shrub dynamics and exploring the response of shrublands to past and ongoing climate and land use changes.
Auteurs, date et publication :
Auteurs Arthur Bayle , Bradley Z. Carlson , Baptiste Nicoud , Loïc Francon , Christophe Corona , Sandra Lavorel , Philippe Choler
Publication : Frontiers of Biogeography
Date : 2025
Volume : 16
Issue : 1
Catégorie(s)
#CNRS #Lautaret #UGARésumé
The importance of biota to soil formation and landscape development is widely recognized. As biotic complexity increases during early succession via colonization by soil microbes followed by vascular plants, effects of biota on mineral weathering and soil formation become more complex. Knowledge of the interactions among groups of organisms and environmental conditions will enable us to better understand landscape evolution. Here, we used experimental columns of unweathered granular basalt to investigate how early successional soil microbes, vascular plants (alfalfa; Medicago sativa), and soil moisture interact to affect both plant performance and mineral weathering. We found that the presence of soil microbes reduced plant growth rates, total biomass, and survival, which suggests that plants and microbes were competing for nutrients in this environment. However, we also found considerable genotype-specific variation in plant–microbial interactions, which underscores the importance of within-species genetic variation on biotic interactions. We also found that the presence of vascular plants reduced variability in pH and electrical conductivity, suggesting that plants may homogenize weathering reactions across the soil column. We also show that there is heterogeneity in the abiotic conditions in which microbes, plants, or their combination have the strongest effect on weathering, and that many of these relationships are sensitive to soil moisture. Our findings highlight the importance of interdependent effects of environmental and biotic factors on weathering during initial landscape formation.
Auteurs, date et publication :
Auteurs Valerie R. Milici , Samuel Abiven , Hannes H. Bauser , Lily G. Bishop , Rebecca G. W. Bland , Jon Chorover , Katerina M. Dontsova , Kielah Dyer , Linus Friedman , Matthew J. Rusek-Peterson , Scott Saleska , Katrina M. Dlugosch
Publication : Geobiology
Date : 2025
Volume : 22
Issue : 6
Pages : e70004
Catégorie(s)
#CNRS #Ecotron de Montpellier #Ecotron IleDeFrance #ENSRésumé
NATURE-BASED SOLUTIONS: An important lever for mitigating climate change, only if they come with a drastic reduction in greenhouse gas emissions Ongoing climate change calls for strong responses, in particular to reduce greenhouse gas emissions. However, even a drastic reduction in greenhouse gas emissions will not enable to achieve the targets set by the Paris Agreement of global warming below 2 °C, a fortiori 1.5°C. This objective is still achievable if the imperative reduction in emissions is accompanied by the implementation of negative emission technologies aiming at transferring and storing the carbon dioxide from the atmosphere into a different form that has no impact on the climate. These technologies include nature-based solutions. In this article, we present part of the available portfolio on land surfaces by summarizing the literature. We present their potential and their limitations, and recall the importance of an integrated vision of ecosystem management, which needs to be multi-objective.
Auteurs, date et publication :
Auteurs B Guenet , J Le Noë
Publication : Etude et Gestion des Sols
Date : 2025
Volume : 31