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1. Peatland microhabitat heterogeneity drives phototrophic microbe distribution and photosynthetic activity

Author: Régis Céréghino, Martin Küttim, Samuel Hamard, Vincent E. J. Jassey, Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), and ANR-17-CE01-0007,MIXOPEAT,Repenser le cycle du carbone des tourbières : identifier le rôle des protistes mixotrophes dans la pompe à carbone biologique(2017)
Subjects: 0106 biological sciences, Microbial diversity, Peat, Algae, Peatland, Soil carbon uptake, Forests, 010603 evolutionary biology, 01 natural sciences, Microbiology, Sphagnum, [SDV.MP.PRO]Life Sciences [q-bio]/Microbiology and Parasitology/Protistology, Soil, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, Sphagnopsida, Dominance (ecology), Photosynthesis, Ecology, Evolution, Behavior and Systematics, Soil Microbiology, ComputingMilieux_MISCELLANEOUS, Abiotic component, Biomass (ecology), biology, Phototroph, Ecology, 010604 marine biology & hydrobiology, Soil carbon, Carbon cycle, Phototrophs, 15. Life on land, biology.organism_classification, Light intensity, 13. Climate action, Metabarcoding, Primary productivity
Abstract: Phototrophic microbes are widespread in soils, but their contribution to soil carbon (C) uptake remains underexplored in most terrestrial systems, including C-accreting systems such as peatlands. Here, by means of metabarcoding and ecophysiological measurements, we examined how microbial photosynthesis and its biotic (e.g., phototrophic community structure, biomass) and abiotic drivers (e.g., Sphagnum moisture, light intensity) vary across peatland microhabitats. Using a natural gradient of microhabitat conditions from pool to forest, we show that the structure of phototrophic microbial communities shifted from a dominance of eukaryotes in pools to prokaryotes in forests. We identified five groups of co-occurring phototrophic operational taxonomic units with specific environmental preferences across the gradient. Along with such structural changes, we found that microbial C uptake was the highest in the driest and shadiest microhabitats. This study renews and improves current views on phototrophic microbes in peatlands, as the contribution of microbial photosynthesis to peatland C uptake has essentially been studied in wet microhabitats.
Published: 2021
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2. Come Rain, Come Shine: Peatland Carbon Dynamics Shift Under Extreme Precipitation

Author: Anna Sytiuk, Vincent Moulia, Janna M. Barel, Samuel Hamard, Vincent E. J. Jassey, Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Biotechnologie de l'Environnement [Narbonne] (LBE), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Gestion de l'Eau, Acteurs, Usages (UMR G-EAU), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut de Recherche pour le Développement (IRD)-AgroParisTech-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Fondation pour la Recherche sur la Biodiversite which acted in cooperation with the French Agency for Biodiversity (AFB), and its partners (FRB-www.fondationbiodiversite.fr), ANR-17-CE01-0007,MIXOPEAT,Repenser le cycle du carbone des tourbières : identifier le rôle des protistes mixotrophes dans la pompe à carbone biologique(2017), Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut Agro - Montpellier SupAgro, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), and Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut de Recherche pour le Développement (IRD)-AgroParisTech-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut Agro - Montpellier SupAgro
Subjects: 0106 biological sciences, Peat, 010504 meteorology & atmospheric sciences, Water table, Growing season, Atmospheric sciences, 010603 evolutionary biology, 01 natural sciences, Mesocosm, resistance, chemistry.chemical_compound, Dissolved organic carbon, GE1-350, Ecosystem, Precipitation, resilience, 0105 earth and related environmental sciences, General Environmental Science, [SDV.EE]Life Sciences [q-bio]/Ecology, environment, decomposition, rewetting, methane, water table fluctuation, carbon dioxide, 15. Life on land, dissolved organic carbon, Environmental sciences, chemistry, 13. Climate action, Carbon dioxide, Environmental science
Abstract: Precipitation patterns are becoming increasingly extreme, particularly at northern latitudes. Current climate models predict that this trend will continue in the future. While droughts have been repeatedly studied in many ecosystems over the last decades, the consequences of increasingly intense, but less frequent rainfall events, on carbon (C) cycling are not well understood. At northern latitudes, peatlands store one third of the terrestrial carbon and their functioning is highly dependent on water. Shifts in rainfall regimes could disrupt peatland C dynamics and speed-up the rates of C loss. How will these immense stocks of C be able to withstand and recover from extreme rainfall? We tested the resistance and resilience effects of extreme precipitation regimes on peatland carbon dioxide (CO2) and methane (CH4) fluxes, pore water dissolved organic carbon (DOC) and litter decomposition rates by exposing intact peat cores to extreme, spring-time rainfall patterns in a controlled mesocosm experiment. We find that more intense but less frequent rainfall destabilized water table dynamics, with cascading effects on peatland C fluxes. Decomposition and respiration rates increased with a deeper mean water table depth (WTD) and larger WTD fluctuations. We observed similar patterns for CO2 uptake, which were likely mediated by improved vascular plant performance. After a three-week recovery period, CO2 fluxes still displayed responses to the earlier WTD dynamics, suggesting lagged effects of precipitation regime shifts. Furthermore, we found that CH4 emissions decreased with deeper mean WTD, but this showed a high resilience once WTD dynamics stabilised. Not only do our results illustrate that shifting rainfall patterns translate in altered WTD dynamics and, consequentially, influence C fluxes, they also demonstrate that exposure to altered rainfall early in the growing season can have lasting effects on CO2 exchange. Even though the increased CO2 assimilation under extreme precipitation patterns signals peatland resistance under changing climatic conditions, it may instead mark the onset of vascular plant encroachment and the associated C loss.
Published: 2021
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3. When water runs dry — peatland C dynamic under extreme droughts

Author: Vincent E. J. Jassey, Janna M. Barel, and Mariusz Lamentowicz
Subjects: Hydrology, Peat, Environmental science
Abstract: Ecosystems are increasingly exposed to climatic extremes, such as drought and extreme rainfall patterns. Recent studies evidenced the strong variability in ecosystem’s response to droughts, raising the issue of non-linear responses in ecosystem’s carbon (C) dynamic. The conundrum is what causes C fluxes to shift in response to drought, and most importantly, does such extreme events have lasting effects? Here, we will synthesize the results from three different studies testing the effect of droughts and/or extreme rainfall patterns on peatland CO2 fluxes.In a first experiment, we tested the resistance and resilience effects of extreme rainfall patterns on peatland C fluxes in a mesocosm experiment. We found that increasingly intense but less frequent rainfall, with longer intermediate dry periods, destabilises water table dynamic, with cascading effects on peatland C fluxes. Yet, peatland C dynamics might be more resilient than expected as vascular plants may fulfil a compensatory role by taking up more C. Moreover, CO2 fluxes displayed lasting influence of extreme rainfall after restoration of the water table dynamics.In a second experiment, we manipulated the water table depth in the field and generated a gradient spanning from -5 to -60 cm. We found that substantial changes in peatland CO2 respiration occurred when the water level fell below a critical point of -24 cm. Around that apparently critical water level, we showed that plant and fungal communities were suddenly altered and raised CO2 respiration rates.In the last experiment, we tested the combined effect of prolonged drought and warming on the C uptake of two Sphagnum species. We found that the effect of climate warming on Sphagnum community photosynthesis toggles from positive to negative as the peatland goes from rainy to dry periods during summer. We further found that mechanisms of compensation among the dominant Sphagnum species stabilized the average C uptake of the Sphagnum community over the growing season.As a corollary, our results show that extreme climatic events induce functional transitions in peatland C dynamics. These functional transitions further depends on the phenotypic plasticity among plant and microbial species as well as on the evenness of specific functional groups that modulate the effects of droughts on peatland C dynamic.
Published: 2021
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4. Rewiring of peatland plant-microbe networks outpaces species turnover

Author: Vincent E. J. Jassey, Bo H. Svensson, Bjorn J. M. Robroek, Marc G. Dumont, Annelies J. Veraart, Magalí Martí, Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Université Fédérale Toulouse Midi-Pyrénées-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), and ANR-17-CE01-0007,MIXOPEAT,Repenser le cycle du carbone des tourbières : identifier le rôle des protistes mixotrophes dans la pompe à carbone biologique(2017)
Subjects: 0106 biological sciences, 16S amplicon sequencing, Ekologi, 0303 health sciences, Peat, plant–microbe interactions, Ecology, microbial and plant diversity, plant-microbe interactions, Plant microbe, Aquatic Ecology, 15. Life on land, bipartite networks, 010603 evolutionary biology, 01 natural sciences, 03 medical and health sciences, Environmental science, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, 16S rRNA, Ecology, Evolution, Behavior and Systematics, ComputingMilieux_MISCELLANEOUS, peatlands, 030304 developmental biology
Abstract: International audience; Enviro-climatic changes are thought to be causing alterations in ecosystem processes through shifts in plant and microbial communities; however, how links between plant and microbial communities change with enviro-climatic change is likely to be less straightforward but may be fundamental for many ecological processes. To address this, we assessed the composition of the plant community and the prokaryotic community-using amplicon-based sequencing-of three European peatlands that were distinct in enviro-climatic conditions. Bipartite networks were used to construct sitespecific plant-prokaryote co-occurrence networks. Our data show that between sites, plant and prokaryotic communities differ and that turnover in interactions between the communities was complex. Essentially, turnover in plant-microbial interactions is much faster than turnover in the respective communities. Our findings suggest that network rewiring does largely result from novel or different interactions between species common to all realised networks. Hence, turnover in network composition is largely driven by the establishment of new interactions between a core community of plants and microorganisms that are shared among all sites. Taken together our results indicate that plant-microbe associations are context dependent, and that changes in enviro-climatic conditions will likely lead to network rewiring. Integrating turnover in plant-microbe interactions into studies that assess the impact of enviro-climatic change on peatland ecosystems is essential to understand ecosystem dynamics and must be combined with studies on the impact of these changes on ecosystem processes.
Published: 2021
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5. Constraints on potential enzyme activities in thermokarst bogs : Implications for the carbon balance of peatlands following thaw

Author: Liam Heffernan, David Olefeldt, M. Derek MacKenzie, Maya Frederickson, Vincent E. J. Jassey, Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université de Toulouse (UT)
Subjects: Peat, 010504 meteorology & atmospheric sciences, thermokarst, Permafrost, chemistry.chemical_element, 01 natural sciences, Sphagnum, Thermokarst, peat pore water, Greenhouse Gases, Soil, organic matter quality, soil enzyme activities, Environmental Chemistry, Bog, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, General Environmental Science, Ekologi, Global and Planetary Change, geography, geography.geographical_feature_category, biology, Ecology, 04 agricultural and veterinary sciences, Soil carbon, 15. Life on land, biology.organism_classification, Decomposition, Carbon, soil organic carbon, chemistry, 13. Climate action, Wetlands, Environmental chemistry, [SDE]Environmental Sciences, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries, Environmental science, peatland, permafrost
Abstract: Northern peatlands store a globally significant amount of soil organic carbon, much of it found in rapidly thawing permafrost. Permafrost thaw in peatlands often leads to the development and expansion of thermokarst bogs, where microbial activity will determine the stability of the carbon storage and the release of greenhouse gases. In this study, we compared potential enzyme activities between young (thawed ~30 years ago) and mature (~200 years) thermokarst bogs, for both shallow and deep peat layers. We found very low potential enzyme activities in deep peat layers, with no differences between the young and mature bogs. Peat quality at depth was found to be highly humified (FTIR analysis) in both the young and mature bogs. This suggests that deep, old peat was largely stable following permafrost thaw, without a rapid pulse of decomposition during the young bog stage. For near-surface peat, we found significantly higher potential enzyme activities in the young bog than in the mature-associated with differences in peat quality derived from different Sphagnum species. A laboratory incubation of near-surface peat showed that differences in potential enzyme activity were primarily influenced by peat type rather than oxygen availability. This suggested that the young bog can have higher rates of near-surface decomposition despite being substantially wetter than the mature bog. Overall, our study shows that peat properties are the dominant constraint on potential enzyme activity and that peatland site development (successional pathways and permafrost history) through its influence on peat type and chemistry is likely to determine peat decomposition following permafrost thaw.
Published: 2021
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6. Functional diversity and trait composition of vascular plant and Sphagnum moss communities during peatland succession across land uplift regions

Author: Eeva-Stiina Tuittila, Anna M. Laine, Oleg Kutznetsov, Mats Nilsson, Vincent E. J. Jassey, Tapio Lindholm, Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université de Toulouse (UT)
Subjects: 0106 biological sciences, hiilidioksidi, Peat, Plant Science, Ecological succession, muutos, 01 natural sciences, Sphagnum, Russia, sammalet, Mire, conservative species, plant economic spectrum, suot, functional traits, Bog, intraspecific variability, ComputingMilieux_MISCELLANEOUS, Finland, geography.geographical_feature_category, biology, Ecology, pH, phylogenetic signal, vascular plant, food and beverages, functional diversity, succession, communities, climate change, environmental perturbations, ecosystems, Vascular plant, Autogenic succession, coastal areas, 010603 evolutionary biology, moss, resistance, kasvit, rannikot, peat thickness, Ecology, Evolution, Behavior and Systematics, peatlands, Sweden, geography, acquisitive species, trait composition, carbon, fungi, Plant community, coastal regions, 15. Life on land, ilmastonmuutokset, biology.organism_classification, luonnon monimuotoisuus, peatland development, biodiversiteetti, ekosysteemit (ekologia), land uplift regions, resistance to climate change, coasts, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, 010606 plant biology & botany
Abstract: 1. Most of the carbon accumulated into peatlands is derived from Sphagnum mosses. During peatland development, the relative share of vascular plants and Sphagnum mosses in the plant community changes, which impacts ecosystem functions. Little is known on the successional development of functional plant traits or functional diversity in peatlands, although this could be a key for understanding the mechanisms behind peatland resistance to climate change. Here we aim to assess how functionality of successive plant communities change along the autogenic peatland development and the associated environmental gradients, namely peat thickness and pH, and to determine whether trait trade-offs during peatland succession are analogous between vascular plant and moss communities. 2. We collected plant community and trait data on successional peatland gradients from post-glacial rebound areas in coastal Finland, Sweden and Russia, altogether from 47 peatlands. This allowed us to analyse the changes in community-weighted mean trait values and functional diversity (diversity of traits) during peatland development. 3. Our results show comparative trait trade-offs from acquisitive species to conservative species in both vascular plant and Sphagnum moss communities during peatland development. However, mosses had higher resistance to environmental change than vascular plant communities. This was seen in the larger proportion of intraspecific trait variation than species turnover in moss traits, while the proportions were opposite for vascular plants. Similarly, the functional diversity of Sphagnum communities increased during the peatland development, while the opposite occurred for vascular plants. Most of the measured traits showed a phylogenetic signal. More so, the species common to old successional stages, namely Ericacae and Sphagna from subgroup Acutifolia were detected as most similar to their phylogenetic neighbours. 4. Synthesis. During peatland development, vegetation succession leads to the dominance of conservative plant species accustomed to high stress. At the same time, the autogenic succession and ecological engineering of Sphagna leads to higher functional diversity and intraspecific variability, which together indicate higher resistance towards environmental perturbations.
Published: 2021
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7. Contribution of microbial photosynthesis to peatland carbon uptake along a latitudinal gradient

Author: Joséphine Leflaive, Régis Céréghino, Samuel Hamard, Eeva-Stiina Tuittila, Maialen Barret, Gaël Le Roux, Paul Kardol, Ellen Dorrepaal, Anna Sytiuk, Enrique Lara, Vincent E. J. Jassey, Mariusz Lamentowicz, Martin Küttim, Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, Real Jardín Botánico de Madrid, Spanish National Research Council (CSIC), Umeå University, Swedish University of Agricultural Sciences (SLU), Tallinn University, Adam Mickiewicz University in Poznań (UAM), University of Eastern Finland, Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Real Jardín Botánico de Madrid (RJB), and ANR-17-CE01-0007,MIXOPEAT,Repenser le cycle du carbone des tourbières : identifier le rôle des protistes mixotrophes dans la pompe à carbone biologique(2017)
Subjects: 0106 biological sciences, Microbial diversity, Peat, Algae, Peatland, Plant Science, Photosynthesis, 010603 evolutionary biology, 01 natural sciences, Carbon cycle, 03 medical and health sciences, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, Ecology, Evolution, Behavior and Systematics, 030304 developmental biology, 2. Zero hunger, 0303 health sciences, Carbon dioxide in Earth's atmosphere, Ecology, biology, Phototroph, Community structure, Phototrophs, 15. Life on land, biology.organism_classification, [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology, 13. Climate action, Metabarcoding, Primary productivity, Environmental science, Terrestrial ecosystem
Abstract: International audience; Phototrophic microbes, also known as micro-algae, display a high abundance in many terrestrial surface soils. They contribute to atmospheric carbon dioxide fluxes through their photosynthesis, and thus regulate climate similar to plants. However, microbial photosynthesis remains overlooked in most terrestrial ecosystems. Here, we hypothesize that phototrophic microbes significantly contribute to peatland C uptake, unless environmental conditions limit their development and their photosynthetic activity.To test our hypothesis, we studied phototrophic microbial communities in five peatlands distributed along a latitudinal gradient in Europe. By means of metabarcoding, microscopy and cytometry analyses, as well as measures of photosynthesis, we investigated the diversity, absolute abundance and photosynthetic rates of the phototrophic microbial communities.We identified 351 photosynthetic prokaryotic and eukaryotic operational taxonomic units (OTU) across the five peatlands. We found that water availability and plant composition were important determinants of the composition and the structure of phototrophic microbial communities. Despite environmental shifts in community structure and composition, we showed that microbial C-fixation rates remained similar along the latitudinal gradient. Our results further revealed that phototrophic microbes accounted for approximately 10% of peatland C uptake.Synthesis. Our findings show that phototrophic microbes are extremely diverse and abundant in peatlands. While species turnover with environmental conditions, microbial photosynthesis similarly contributed to peatland C uptake at all latitudes. We estimate that phototrophic microbes take up around 75 MT CO2 per year in northern peatlands. This amount roughly equals the magnitude of projected peatland C loss due to climate warming and highlight the importance of phototrophic microbes for the peatland C cycle
Published: 2021
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8. Predicting the structure and functions of peatland microbial communities from Sphagnum phylogeny, anatomical and morphological traits and metabolites

Author: Bertrand Pourrut, Régis Céréghino, Ellen Dorrepaal, Mariusz Lamentowicz, Amélie Guittet, Anna Sytiuk, Samuel Hamard, Eeva-Stiina Tuittila, Martin Küttim, Janna M. Barel, Vincent E. J. Jassey, Frédéric Delarue, Bjorn J. M. Robroek, Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Milieux Environnementaux, Transferts et Interactions dans les hydrosystèmes et les Sols (METIS), École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), ANR-17-CE01-0007,MIXOPEAT,Repenser le cycle du carbone des tourbières : identifier le rôle des protistes mixotrophes dans la pompe à carbone biologique(2017), Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), École pratique des hautes études (EPHE), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, 0303 health sciences, Peat, Ecology, biology, Aquatic Ecology, Plant Science, 15. Life on land, biology.organism_classification, 010603 evolutionary biology, 01 natural sciences, Sphagnum, 03 medical and health sciences, Metabolomics, Phylogenetics, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Ecology, Evolution, Behavior and Systematics, ComputingMilieux_MISCELLANEOUS, 030304 developmental biology
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Published: 2021
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9. Assessing the responses of Sphagnum micro-eukaryotes to climate changes using high throughput sequencing

Author: Matthieu Mulot, Vincent E. J. Jassey, Christophe V. W. Seppey, Sandra Słowińska, Mariusz Lamentowicz, Monika Reczuga, Enrique Lara, Michał Słowiński, Alexandre Buttler, Edward A. D. Mitchell, Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université de Toulouse (UT)
Subjects: 0106 biological sciences, VDP::Mathematics and natural science: 400::Zoology and botany: 480::Ecology: 488, Peat, warming, Biodiversity, lcsh:Medicine, Climate change, Biology, 010603 evolutionary biology, 01 natural sciences, General Biochemistry, Genetics and Molecular Biology, wetlands, diversity, Carbon cycle, food-web, VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Økologi: 488, 03 medical and health sciences, carbon-cycle, patterns, Ecosystem, ComputingMilieux_MISCELLANEOUS, biodiversity, 030304 developmental biology, protists, 2. Zero hunger, 0303 health sciences, Ecology, General Neuroscience, lcsh:R, Global warming, temperature, General Medicine, Soil carbon, 15. Life on land, populations, 13. Climate action, short-term, impact, water table manipulation, peatland, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, community structure, Ecosystem respiration, General Agricultural and Biological Sciences, testate amebas
Abstract: Current projections suggest that climate warming will be accompanied by more frequent and severe drought events. Peatlands store ca. one third of the world’s soil organic carbon. Warming and drought may cause peatlands to become carbon sources through stimulation of microbial activity increasing ecosystem respiration, with positive feedback effect on global warming. Micro-eukaryotes play a key role in the carbon cycle through food web interactions and therefore, alterations in their community structure and diversity may affect ecosystem functioning and could reflect these changes. We assessed the diversity and community composition of Sphagnum-associated eukaryotic microorganisms inhabiting peatlands and their response to experimental drought and warming using high throughput sequencing of environmental DNA. Under drier conditions, micro-eukaryotic diversity decreased, the relative abundance of autotrophs increased and that of osmotrophs (including Fungi and Peronosporomycetes) decreased. Furthermore, we identified climate change indicators that could be used as early indicators of change in peatland microbial communities and ecosystem functioning. The changes we observed indicate a shift towards a more “terrestrial” community in response to drought, in line with observed changes in the functioning of the ecosystem.
Published: 2020
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10. Author response for 'Functional diversity and trait composition of vascular plant and Sphagnum moss communities during peatland succession across land uplift regions'

Author: Tapio Lindholm, Mats Nilsson, Oleg Kutznetsov, Eeva-Stiina Tuittila, Vincent E. J. Jassey, and Anna Laine
Subjects: Vascular plant, Geography, Peat, biology, Ecology, Trait, Land uplift, Composition (visual arts), Ecological succession, biology.organism_classification, Sphagnum, Moss
Published: 2020
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11. Unveiling tipping points in long-term and experimental studies in peatlands

Author: Katarzyna Marcisz, Vincent E. J. Jassey, Michał Słowiński, and Mariusz Lamentowicz
Subjects: Peat, Environmental science, Physical geography, Term (time)
Abstract: Ecosystems are increasingly prone to climate extremes, such as drought, with long-lasting effects on both plant and soil communities and, subsequently, on carbon (C) cycling. Unveiling past tipping points is a prerequisite for a better understanding of how individual species and entire ecosystems will respond to future climate changes, especially soil moisture. In the first study we identified the response of peatland vegetation to shifts in hydrological conditions over the past 2000 years using plant macrofossils, testate amoebae-based quantitative hydrological reconstructions from seven Polish peat-records (Lamentowicz et al., 2019). Using threshold indicator taxa analysis (TITAN), we discovered that plant community composition strongly converged at a water level of c. 11.7 cm, indicating a community-level tipping-point. We identified 45 plant taxa that showed either an increase or a decrease in their relative abundance between 8 and 17 cm of water level depth. In other the experimental study (Jassey et al., 2018) we investigated the response of plant and soil fungi to drought of different intensities using a water table gradient in peatlands—a major C sink ecosystem. We show that substantial changes in ecosystem respiration, plant and soil fungal communities occurred when the water level fell below a tipping point of 24 cm. As a corollary, ecosystem respiration was the greatest when graminoids and saprotrophic fungi became prevalent as a response to the extreme drought. Graminoids indirectly influenced fungal functional composition and soil enzyme activities through their direct effect on dissolved organic matter quality, while saprotrophic fungi directly influenced soil enzyme activities. In turn, increasing enzyme activities promoted ecosystem respiration. We show that functional transitions in ecosystem respiration critically depend on the degree of response of graminoids and saprotrophic fungi to drought. Our results represent a major advance in understanding the nonlinear nature of ecosystem properties to drought and pave the way towards a truly mechanistic understanding of tipping points in peatlands with use of experiment and palaeoecology.ReferencesJassey, V.E.J., Reczuga, M.K., Zielinska, M., Slowinska, S., Robroek, B.J.M., Mariotte, P., Seppey, C.V.W., Lara, E., Barabach, J., Slowinski, M., Bragazza, L., Chojnicki, B.H., Lamentowicz, M., Mitchell, E.A.D., Buttler, A., 2018. Tipping point in plant-fungal interactions under severe drought causes abrupt rise in peatland ecosystem respiration. Glob Chang Biol. 24, (3) 972–986.Lamentowicz, M., Gałka, M., Marcisz, K., Słowiński, M., Kajukało-Drygalska, K., Dayras, M.D., Jassey, V.E.J., 2019. Unveiling tipping points in long-term ecological records from Sphagnum -dominated peatlands. Biology Letters. 15, (4) 20190043.
Published: 2020
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12. From Climatic to Anthropogenic Drivers: A Multi-Proxy Reconstruction of Vegetation and Peatland Development in the French Jura Mountains

Author: Daniel Gilbert, Frédéric Delarue, Emilie Gauthier, Richard J. Payne, Vincent E. J. Jassey, Edward A. D. Mitchell, Mariusz Lamentowicz, Hervé Richard, Fatima Laggoun-Défarge, Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Université de Neuchâtel (UNINE), Laboratory ofWetland Ecology and Monitoring, and Department of Biogeography and Paleoecology, Adam Mickiewicz University in Poznań (UAM), Environment and Geography, University of York, Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Biogéosystèmes Continentaux - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), ANR-07-VULN-0010,PEATWARM,Impact du réchauffement climatique sur la focntion de puits de carbone de l'ecosysteme tourbières à sphaignes.(2007), Laboratoire Chrono-environnement (UMR 6249) (LCE), Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC)
Subjects: 010506 paleontology, Peat, human impact, 010504 meteorology & atmospheric sciences, 01 natural sciences, law.invention, Jura Mountains, law, Evapotranspiration, Mire, Earth and Planetary Sciences (miscellaneous), Radiocarbon dating, Testate amoebae, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, palynology, climate, Holocene, 0105 earth and related environmental sciences, Earth-Surface Processes, Palynology, Vegetation, 15. Life on land, testate amoebae, [SDU]Sciences of the Universe [physics], Environmental science, Physical geography
Abstract: International audience; A 4 m core was extracted from the center of a peatland located in the Drugeon valley (France). Thirteen radiocarbon dates were used to build a robust age model. Testate amoebae were used for reconstructing mire surface wetness. High-resolution pollen analysis of the sequence reconstructed 9 millennia of development of the peatland and its surrounding vegetation. During the early/middle Holocene (9500 to 5800 cal BP), warm conditions led to high evapotranspiration and low water levels. The vegetation history is characterized by the development of a Pinus and a mixed Quercus forest. From 5800 cal BP, testate amoebae show wetter conditions, indicating the onset of the cooler Neoglacial period. The cooling is also evidenced by the development of Abies and Fagus trees, replacing the oak forest. The first indicators of human impact appear at about 4800 cal BP, and indicators of farming activity remains very rare until ca. 2600 cal BP, at the beginning of the Iron Age. The development of the peatland responded to climatic fluctuation until 2600 cal BP, after which human impact became the main driver. The last millennium has been characterized by sudden drying and the spread of pine on the peatland.
Published: 2019
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13. Effects of climate warming on Sphagnum photosynthesis in peatlands depend on peat moisture and species‐specific anatomical traits

Author: Constant Signarbieux, Vincent E. J. Jassey, Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), and Laboratory of Geographic Information Systems (LASIG), School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL)
Subjects: 0106 biological sciences, Peat, 010504 meteorology & atmospheric sciences, Climate Change, Rain, [SDE.MCG]Environmental Sciences/Global Changes, Climate change, 010603 evolutionary biology, 01 natural sciences, Sphagnum, Soil, Sphagnopsida, Environmental Chemistry, Ecosystem, Photosynthesis, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, General Environmental Science, Global and Planetary Change, Ecology, biology, Global warming, 15. Life on land, biology.organism_classification, Sphagnum magellanicum, Photosynthetic capacity, Sphagnum fallax, 13. Climate action, Environmental science
Abstract: Climate change will influence plant photosynthesis by altering patterns of temperature and precipitation, including their variability and seasonality. Both effects may be important for peatlands as the carbon (C) sink potential of these ecosystems depends on the balance between plant C uptake through photosynthesis and microbial decomposition. Here, we show that the effect of climate warming on Sphagnum community photosynthesis toggles from positive to negative as the peatland goes from rainy to dry periods during summer. More particularly, we show that mechanisms of compensation among the dominant Sphagnum species (Sphagnum fallax and Sphagnum medium) stabilize the average photosynthesis and productivity of the Sphagnum community during summer despite rising temperatures and frequent droughts. While warming had a negligible effect on S. medium photosynthetic capacity (Amax ) during rainy periods, Amax of S. fallax increased by 40%. On the opposite, warming exacerbated the negative effects of droughts on S. fallax with an even sharper decrease of its Amax while S. medium Amax remained unchanged. S. medium showed a remarkable resistance to droughts due to anatomical traits favouring its water holding capacity. Our results show that different phenotypic plasticity among dominant Sphagnum species allow the community to cope with rising temperatures and repeated droughts, maintaining similar photosynthesis and productivity over summer in warmed and control conditions. These results are important because they provide information on how soil water content may modulate the effects of climate warming on Sphagnum productivity in boreal peatlands. It further confirms the transitory nature of warming-induced photosynthesis benefits in boreal systems and highlights the vulnerability of the ecosystem to excess warming and drying.
Published: 2019
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14. Unveiling tipping points in long-term ecological records from Sphagnum-dominated peatlands

Author: Michał Słowiński, Vincent E. J. Jassey, Katarzyna Kajukało-Drygalska, Mariusz Lamentowicz, Milva Druguet Dayras, Katarzyna Marcisz, Mariusz Gałka, Adam Mickiewicz University in Poznań (UAM), Laboratory of Wetland Ecology and Monitoring, Faculty of Geographical and Geological Sciences, Department of Geoecology and Climatology, Institute of Geography and Spatial Organization, Polska Akademia Nauk = Polish Academy of Sciences (PAN), Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), and Polish Academy of Sciences
Subjects: 0106 biological sciences, Peat, 010504 meteorology & atmospheric sciences, media_common.quotation_subject, 010603 evolutionary biology, 01 natural sciences, Sphagnum, Corrections, Sphagnopsida, Ecosystem, Amoeba, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, media_common, biology, Ecology, Biodiversity, 15. Life on land, Future climate, biology.organism_classification, Agricultural and Biological Sciences (miscellaneous), Term (time), Critical transition, Psychological resilience, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, General Agricultural and Biological Sciences
Abstract: Unveiling past tipping points is a prerequisite for a better understanding of how individual species and entire ecosystems will respond to future climate change. Such knowledge is key for the implementation of biodiversity conservation. We identify the relationships between peatland vegetation and hydrological conditions over the past 2000 years using plant macrofossils, testate amoebae-based quantitative hydrological reconstructions and Sphagnum -moss functional traits from seven Polish peatland records. Using threshold indicator taxa analysis, we discovered that plant community composition strongly converged at a water level of ca 11.7 cm, indicating a community-level tipping point. We identified 45 plant taxa that showed either an increase or a decrease in their relative abundance between 8 and 17 cm of water-level depth. Our analysis of Sphagnum community traits further showed that Sphagnum functional diversity was remarkably stable over time despite Sphagnum species sensitivity to hydrological conditions. Our results suggest that past hydrological shifts did not influence major functions of the Sphagnum community, such as photosynthetic capacity, growth and productivity, owing to species replacement with a similar functional space. Although further studies including trait plasticity will be required, our findings suggest that the capacity of the Sphagnum community to gain carbon remained stable despite hydrological changes.
Published: 2019
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15. Unveiling exceptional Baltic bog ecohydrology, autogenic succession and climate change during the last 2000 years in CE Europe using replicate cores, multi-proxy data and functional traits of testate amoebae

Author: Willem Oscar van der Knaap, Mariusz Gałka, Vasile Ersek, Łukasz Lamentowicz, Kazimierz Tobolski, Vincent E. J. Jassey, Mariusz Lamentowicz, Adam Mickiewicz University in Poznań (UAM), University of Northumbria at Newcastle [United Kingdom], Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratory of Wetland Ecology and Monitoring, and Faculty of Geographical and Geological Sciences, Adam Mickiewicz University
Subjects: Autogenic succession, 010506 paleontology, Archeology, Peat, Peatland, 010504 meteorology & atmospheric sciences, F400, Climate change, F800, 01 natural sciences, Sphagnum, Ecohydrology, Mire, Testate amoebae, Bog, ComputingMilieux_MISCELLANEOUS, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, Global and Planetary Change, geography, geography.geographical_feature_category, Holocene, biology, Ecology, Geology, Sphagnum succession, 15. Life on land, biology.organism_classification, 13. Climate action, [SDE]Environmental Sciences, Pollen, Environmental science, Palaeohydrology, Plant macrofossils
Abstract: We present the results of high-resolution, multi-proxy palaeoecological investigations of two parallel peat cores from the Baltic raised bog Mechacz Wielki in NE Poland. We aim to evaluate the role of regional climate and autogenic processes of the raised bog itself in driving the vegetation and hydrology dynamics. Based on partly synchronous changes in Sphagnum communities in the two study cores we suggest that extrinsic factors (climate) played an important role as a driver in mire development during the bog stage (500-2012 CE). Using a testate amoebae transfer function, we found exceptionally stable hydrological conditions during the last 2000 years with a relatively high water table and lack of local fire events that allowed for rapid peat accumulation (2.75 mm/year) in the bog. Further, the strong correlation between pH and community-weighted mean of testate amoeba traits suggests that other variables than water-table depth play a role in driving microbial properties under stable hydrological conditions. There is a difference in hydrological dynamics in bogs between NW and NE Poland until ca 1500 CE, after which the water table reconstructions show more similarities. Our results illustrate how various functional traits relate to different environmental variables in a range of trophic and hydrological scenarios on long time scales. Moreover, our data suggest a common regional climatic forcing in Mechacz Wielki, Gazwa and Kontolanrahka. Though it may still be too early to attempt a regional summary of wetness change in the southern Baltic region, this study is a next step to better understand the long-term peatland palaeohydrology in NE Europe. (C) 2016 Elsevier Ltd. All rights reserved.
Published: 2017
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16. Testate amoebae taxonomy and trait diversity are coupled along an openness and wetness gradient in pine-dominated Baltic bogs

Author: Monika Karpińska-Kołaczek, Vincent E. J. Jassey, Piotr Kołaczek, Mariusz Lamentowicz, Katarzyna Kajukało-Drygalska, Maciej Gąbka, Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université Fédérale Toulouse Midi-Pyrénées
Subjects: Baltic States, 0301 basic medicine, Peat, Heterotroph, Forests, Microbiology, Sphagnum, 03 medical and health sciences, Amoeba, Testate amoebae, Bog, Relative species abundance, ComputingMilieux_MISCELLANEOUS, Ecosystem, Demography, geography, geography.geographical_feature_category, biology, Ecology, Carbon sink, Biodiversity, 15. Life on land, 030108 mycology & parasitology, biology.organism_classification, Light intensity, 030104 developmental biology, Sunlight, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Hydrology
Abstract: Sphagnum peatlands host a high abundance of protists, especially testate amoebae. Here, we designed a study to investigate the functional diversity of testate amoebae in relation to wetness and forest cover in Baltic bogs. We provided new data on the influence of openness/wetness gradient on testate amoebae communities, showing significant differences in selected testate amoebae (TA) traits. Three key messages emerged from our investigations: 1) we recorded an effect of peatland surface openness on testate amoebae functional traits that led us to accept the hypothesis that TA traits differ according to light intensity and hydrology. Mixotrophic species were recorded in high relative abundance in open plots, whereas they were nearly absent in forested sites; 2) we revealed a hydrological threshold for the occurrence of mixotrophic testate amoebae that might be very important in terms of peatland functioning and carbon sink vs. source context; and 3) mixotrophic species with organic tests were nearly absent in forested sites that were dominated by heterotrophic species with agglutinated or idiosomic tests. An important message from this study is that taxonomy of TA rather indicates the hydrological gradient whereas traits of mixotrophs the openness gradient.
Published: 2020
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17. The Impact of Experimental Temperature and Water Level Manipulation on Carbon Dioxide Release in a Poor Fen in Northern Poland

Author: Kamila M. Harenda, Mariusz Lamentowicz, Bjorn J. M. Robroek, Małgorzata Zielińska, Sandra Słowińska, Bogdan H. Chojnicki, Alexandre Buttler, Mateusz Samson, Michał Słowiński, Vincent E. J. Jassey, Jan Barabach, Department of Geoecology and Climatology, Institute of Geography and Spatial Organization, Polish Academy of Sciences, Institute of Physics [Toruń], Faculty of Physics, Astronomy and Informatics [Toruń], Nicolaus Copernicus University [Toruń]-Nicolaus Copernicus University [Toruń], Laboratory of Wetland Ecology and Monitoring, Faculty of Geographical and Geological Sciences, Adam Mickiewicz University, University of Southampton, Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Laboratoire des systèmes écologiques (ECOS), Ecole Polytechnique Fédérale de Lausanne (EPFL), Faculty of Environment Engineering and Spatial Management, Department of Meteorology, Poznan University of Life Sciences, and Polska Akademia Nauk = Polish Academy of Sciences (PAN)
Subjects: 0106 biological sciences, geography, Peat, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Ecology, Water table, Global warming, Wetland, Atmospheric sciences, 010603 evolutionary biology, 01 natural sciences, chemistry.chemical_compound, chemistry, 13. Climate action, Carbon dioxide, [SDE]Environmental Sciences, Environmental Chemistry, Environmental science, Poor fen, Ecosystem, Ecosystem respiration, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, General Environmental Science
Abstract: Peatlands are ecosystems for which carbon budget relies strongly on the meteorological and hydrological conditions. Here, using a manipulative field experiment, we measured ecosystem respiration (RECO) over two years (2013–2014) in a poor fen in Poland to estimate the carbon emission in a changing climate. The experiment consisted of warming (open-top chambers - OTC) and water table manipulation. The application of OTC increased the mean values of daily maximum air temperature by approx. 1.1–1.8 °C. Warming or the increased water table depth separately resulted in an increase in ecosystem respiration by approx. 0.1 μmol CO2 m−2 s−1 and 0.3 μmol CO2 m−2 s−1, respectively. However, our results show also the additive nature of warming and water table drawdown impact on daily RECO during the studied years (2013–0.80 μmol CO2 m−2 s−1 and 2014–1.16 μmol CO2 m−2 s−1). With the natural dry period event which occurred in 2014, the seasonal RECO increased by approx. 0.2 μmol CO2 m−2 s−1 as compared to the previous year. Projected global warming will therefore significantly enhance C loss from poor fens in this region of Europe.
Published: 2018
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18. Peatland vascular plant functional types affect dissolved organic matter chemistry

Author: Luca Bragazza, Vincent E. J. Jassey, Samuel Hamard, Remy Albrecht, Alexandre Buttler, Adrian Pulgarin, Bjorn J. M. Robroek, University of Southampton, Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des systèmes écologiques (ECOS), and Ecole Polytechnique Fédérale de Lausanne (EPFL)
Subjects: Vascular plant, Biogeochemical cycle, Peat, Plant functional types, 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Soil Science, Plant Science, 01 natural sciences, Carbon cycle, chemistry.chemical_compound, Botany, Dissolved organic carbon, Dissolved organic matter chemistry, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Dissolved organic matter chemistry, Enzymatic activity, FDA, FT-IR, Plant functional types, Plant-soil interactions, Sphagnum-dominated peatlands, Enzymatic activity, Plant-soil interactions, biology, Fluorescein diacetate hydrolysis, Soil organic matter, fungi, Ambientale, food and beverages, 04 agricultural and veterinary sciences, Mineralization (soil science), 15. Life on land, biology.organism_classification, FT-IR, Sphagnum-dominated peatlands, chemistry, 13. Climate action, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries, FDA
Abstract: Northern peatlands are large repositories of carbon. Peatland vascular plant community composition has been functionally associated to a set of biogeochemical processes such as carbon cycling. Yet, we do not fully understand to what extent vascular plant functional types (PFTs) affect the quality of dissolved organic matter, and if there is any feedback on soil microbial activity. Using a longer-term plant removal experiment in a boreo-nemoral peatland in Southern Sweden, we relate the dominance of different vascular plant functional types (i.e. ericoids and graminoids) to the chemistry of the dissolved organic matter (DOM) and microbial enzymatic activities (fluorescein diacetate hydrolysis, FDA). Our results show that PFTs modifies the composition of DOM moieties, with a decrease of low molecular weight organic compounds after vascular plant removal. The decrease of enzymatic activity by up to 68 % in the plant removal plots suggests a reduction in DOM mineralization in the absence of vascular plants. Our results show that plant-derived low molecular organic compounds enhance peatland microbial activity, and suggest that an increase of vascular plant cover in response to climate change can potentially destabilize the OM in peatlands, leading to increased carbon losses.
Published: 2015
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19. Predator-prey mass ratio drives microbial activity under dry conditions in Sphagnum peatlands

Author: Edward A. D. Mitchell, Geneviève Chiapusio, Alexandre Buttler, Monika Reczuga, Vincent E. J. Jassey, Sandra Słowińska, Mariusz Lamentowicz, Philippe Binet, Michał Słowiński, Daniel Gilbert, Matthieu Mulot, Bogdan H. Chojnicki, Laboratory of Wetland Ecology and Monitoring, Faculty of Geographical and Geological Sciences, Adam Mickiewicz University in Poznań (UAM), Department of Biogeography and Palaeontology, Faculty of Geographical and Geological Sciences, Faculty of Biology, Laboratory of Soil Biodiversity, Université de Neuchâtel (UNINE), Jardin Botanique de Neuchâtel, Swiss Federal Research Institute (WSL), Laboratory of System Ecology, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratoire Chrono-environnement (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Centre National de la Recherche Scientifique (CNRS), Faculty of Environment Engineering and Spatial Management, Department of Meteorology, Poznan University of Life Sciences, Department of Geoecology and Climatology, Institute of Geography and Spatial Organization, Polska Akademia Nauk = Polish Academy of Sciences (PAN), Centre Alpin de Recherche sur les Réseaux Trophiques et Ecosystèmes Limniques (CARRTEL), Institut National de la Recherche Agronomique (INRA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Laboratory of System Ecology School Architecture Civil and Environment Engineering, Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Narodowe Centrum Nauki 2015/19/N/NZ8/00172 NN306060940 2015/17/B/ST10/01656, French National Agency for Research ANR-07-VUL-010, Switzerland through the Swiss Contribution to the enlarged European Union PSPB-013/2010, Adam Mickiewicz University in Poznan (AMUP), Laboratoire Chrono-environnement - UFC (UMR 6249) (LCE), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Polish Academy of Sciences, Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut National de la Recherche Agronomique (INRA), Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Biogeochemical cycle, Peat, tourbière, 010504 meteorology & atmospheric sciences, Biodiversité et Ecologie, phenoloxidase, Context (language use), drought, 01 natural sciences, Sphagnum, microbial activity, Biodiversity and Ecology, poor fen, phénoloxydase, Mire, Wetlands, body size, food web, protists, soil moisture, water table manipulation, activité microbienne, Testate amoebae, Ecology, Evolution, Behavior and Systematics, peatlands, 0105 earth and related environmental sciences, Nature and Landscape Conservation, Trophic level, sécheresse, 2. Zero hunger, Ecology, biology, 04 agricultural and veterinary sciences, 15. Life on land, biology.organism_classification, Food web, protiste, 13. Climate action, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries, Environmental science, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract: Mid- to high-latitude peatlands are a major terrestrial carbon stock but become carbon sources during droughts, which are increasingly frequent as a result of climate warming. A critical question within this context is the sensitivity to drought of peatland microbial food webs. Microbiota drive key ecological and biogeochemical processes, but their response to drought is likely to impact these processes. Peatland food webs have, however, been little studied, especially the response of microbial predators. We studied the response of microbial predators (testate amoebae, ciliates, rotifers, and nematodes) living in Sphagnum moss carpet to droughts, and their influence on lower trophic levels and on related microbial enzyme activity. We assessed the impact of reduced water availability on microbial predators in two peatlands using experimental (Linje mire, Poland) and natural (Forbonnet mire, France) water level gradients, reflecting a sudden change in moisture regime (Linje), and a typically drier environment (Forbonnet). The sensitivity of different microbial groups to drought was size dependent; large sized microbiota such as testate amoebae declined most under dry conditions (-41% in Forbonnet and -80% in Linje). These shifts caused a decrease in the predator-prey mass ratio (PPMR). We related microbial enzymatic activity to PPMR; we found that a decrease in PPMR can have divergent effects on microbial enzymatic activity. In a community adapted to drier conditions, decreasing PPMR stimulated microbial enzyme activity, while in extreme drought experiment, it reduced microbial activity. These results suggest that microbial enzymatic activity resulting from food web structure is optimal only within a certain range of PPMR, and that different trophic mechanisms are involved in the response of peatlands to droughts. Our findings confirm the importance of large microbial consumers living at the surface of peatlands on the functioning of peatlands, and illustrate their value as early warning indicators of change.
Published: 2018
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20. Sphagnum Species Modulate their Phenolic Profiles and Mycorrhizal Colonization of Surrounding Andromeda polifolia along Peatland Microhabitats

Author: Leslie A. Weston, Gilles Comte, Marie Laure Toussaint, Philippe Binet, Floriant Bellvert, Geneviève Chiapusio, Alexandre Buttler, Frédéric Delarue, Vincent E. J. Jassey, Centre Alpin de Recherche sur les Réseaux Trophiques et Ecosystèmes Limniques (CARRTEL), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut National de la Recherche Agronomique (INRA), Laboratoire Chrono-environnement - UFC (UMR 6249) (LCE), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, Laboratoire d'Ingénierie des Systèmes Biologiques et des Procédés (LISBP), Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National de la Recherche Agronomique (INRA), Laboratoire d'Ecologie Microbienne - UMR 5557 (LEM), Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Vétérinaire de Lyon (ENVL)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de la Recherche Agronomique (INRA)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS), Graham Centre for Agricultural Innovation, Charles Sturt University, Milieux Environnementaux, Transferts et Interactions dans les hydrosystèmes et les Sols (METIS), École pratique des hautes études (EPHE)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Ecological Systems Laboratory ECOS, Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Federal Institute for Forest, Snow and Avalanche Research WSL, French National Agency [ANR-07-VUL-010], Pays Montbeliard Agglomeration (France), Institut National de la Recherche Agronomique (INRA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Institut National de la Recherche Agronomique (INRA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-Ecole Nationale Vétérinaire de Lyon (ENVL), École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Swiss Federal Institute for Forest, Snow and Landscape Research WSL, ANR-07-VULN-0010,PEATWARM,Impact du réchauffement climatique sur la focntion de puits de carbone de l'ecosysteme tourbières à sphaignes.(2007), Laboratoire Chrono-environnement (UMR 6249) (LCE), Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Université de Lyon-Université de Lyon-Ecole Nationale Vétérinaire de Lyon (ENVL)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-Centre National de la Recherche Scientifique (CNRS), MetaToul FluxoMet (TBI-MetaToul), MetaboHUB-MetaToul, MetaboHUB-Génopole Toulouse Midi-Pyrénées [Auzeville] (GENOTOUL), Université de Toulouse (UT)-Université de Toulouse (UT)-Ecole Nationale Vétérinaire de Toulouse (ENVT), Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-MetaboHUB-Génopole Toulouse Midi-Pyrénées [Auzeville] (GENOTOUL), Université de Toulouse (UT)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Toulouse Biotechnology Institute (TBI), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Toulouse Biotechnology Institute (TBI), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Charles Sturt University [Australia], École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)
Subjects: 0106 biological sciences, Peat, tourbière, heathland, 01 natural sciences, Biochemistry, Sphagnum, Plant Roots, peatland microhabitats, Soil, Abundance (ecology), bryophytes, Mycorrhizae, plant soil-interactions, Colonization, Mycorrhiza, Chromatography, High Pressure Liquid, Principal Component Analysis, biology, plants, 04 agricultural and veterinary sciences, General Medicine, carbon loss, Sphagnum magellanicum, symbiosis, Sphagnum fallax, phenolic profiles, gradient, mycorrhizal colonization, mycorhize, Ericaceae, Seasons, Ericaceous Andromeda polifolia, substrat de mousse de sphaigne, Spectrometry, Mass, Electrospray Ionization, mycorrhiza, Phenols, evolution, Botany, Sphagnopsida, global change, Ecology, Evolution, Behavior and Systematics, Allelopathy, Ecosystem, peatlands, Water, 15. Life on land, Sphagnum mosses, biology.organism_classification, allelopathy, responses, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries, profil phénolique, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, 010606 plant biology & botany
Abstract: Sphagnum mosses mediate long-term carbon accumulation in peatlands. Given their functional role as keystone species, it is important to consider their responses to ecological gradients and environmental changes through the production of phenolics. We compared the extent to which Sphagnum phenolic production was dependent on species, microhabitats and season, and how surrounding dwarf shrubs responded to Sphagnum phenolics. We evaluated the phenolic profiles of aqueous extracts of Sphagnum fallax and Sphagnum magellanicum over a 6-month period in two microhabitats (wet lawns versus dry hummocks) in a French peatland. Phenolic profiles of water-soluble extracts were measured by UHPLC-QTOF-MS. Andromeda polifolia mycorrhizal colonization was quantified by assessing the intensity of global root cortex colonization. Phenolic profiles of both Sphagnum mosses were species-, season- and microhabitat- dependant. Sphagnum-derived acids were the phenolics mostly recovered; relative quantities were 2.5-fold higher in S. fallax than in S. magellanicum. Microtopography and vascular plant cover strongly influenced phenolic profiles, especially for minor metabolites present in low abundance. Higher mycorrhizal colonization of A. polifolia was found in lawns as compared to hummocks. Mycorrhizal abundance, in contrast to environmental parameters, was correlated with production of minor phenolics in S. fallax. Our results highlight the close interaction between mycorrhizae such as those colonizing A. polifolia and the release of Sphagnum phenolic metabolites and suggest that Sphagnum-derived acids and minor phenolics play different roles in this interaction. This work provides new insight into the ecological role of Sphagnum phenolics by proposing a strong association with mycorrhizal colonization of shrubs.
Published: 2018
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21. Reconstructing climate change and ombrotrophic bog development during the last 4000years in northern Poland using biotic proxies, stable isotopes and trait-based approach

Author: Mariusz Gałka, Norbert Kühl, Mariusz Lamentowicz, Vincent E. J. Jassey, Milena Obremska, Łukasz Lamentowicz, Andreas Lücke, Department of Biogeography and Paleoecology, Adam Mickiewicz University in Poznań (UAM), and Swiss Federal Institute for Forest, Snow and Landscape Research WSL
Subjects: 010506 paleontology, geography, geography.geographical_feature_category, Peat, 010504 meteorology & atmospheric sciences, Ecology, [SDE.MCG]Environmental Sciences/Global Changes, Paleontology, Ombrotrophic, Climate change, Macrofossil, Vegetation, 15. Life on land, Oceanography, 01 natural sciences, 13. Climate action, Mire, 14. Life underwater, Testate amoebae, Bog, ComputingMilieux_MISCELLANEOUS, Ecology, Evolution, Behavior and Systematics, Geology, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract: article i nfo In this study, we present a record spanning the last 4000 years from a Baltic bog (Kusowskie Bagno) in northern Poland. Using numerous biotic and abiotic proxies, such as testate amoebae (depth to water table reconstruc- tions), stable carbon isotopes ( 13 C), plant macrofossils (proxies for local vegetation and mire surface wetness), pollen and spores (proxies for regional vegetation and human impact), we reconstructed and identified the re- gional hydro-climatic signal of Kusowskie Bagno bog and compared it to other bog records around the Baltic Sea. Our aims were to: 1) combine the species traits of bryophytes and testate amoebae, and more common proxies (isotopes, plant micro-and macro-remains) to infer past peatland development, 2) compare the hydro- climatic signal of Kusowskie Bagno bog to existing records around the Baltic Sea. We found that Kusowskie Bagno bog was very wet during the last 4000 years, and even drainage and peat exploitation had not disturbed its hydrology in northern part in the last 200 years. Carbon isotopes and plant macrofossils were significantly re- latedtospecifictraitsoftestateamoebae,whichinturnreflectedthewatertablechangesoverthelast4000years. Kusowskie Bagno recorded at least the following wet shifts: AD 250, 550, 850, 1250 and 1700, while wet condi- tions occurred during the Migration period at ca AD 550. Furthermore, the testate amoeba-based quantitative wetness reconstruction in Kusowskie Bagno bog resembles the pattern observed in other sites around the Baltic, i.e.,Estonia,Finland,Ireland,northernBritainandthe7500-yearrecordfromthe Stązkibog,northern Poland.Our results provided statistically validated evidence that interactions between plant and microbe need to be more considered further to reconstruct past hydrological. This is the first study of past hydro-climatic changes in peatlands based upon a trait-based approach.
Published: 2015
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22. Impacts of tropospheric ozone exposure on peatland microbial consumers

Author: Vincent E. J. Jassey, Daniel Gilbert, Sylvia Toet, Mike Ashmore, Richard J. Payne, Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Manchester Metropolitan University (MMU), Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Manchester Metropolitan University ( MMU ), Laboratoire d’Ecologie Fonctionnelle, UMR 5245 (CNRS-UPS-INPT), Université P. Sabatier Toulouse III, and Université Paul Sabatier - Toulouse 3 ( UPS )
Subjects: Pollution, Peat, Ozone, 010504 meteorology & atmospheric sciences, media_common.quotation_subject, [SDE.MCG]Environmental Sciences/Global Changes, Air pollution, Soil Science, medicine.disease_cause, 01 natural sciences, Microbiology, [ SDE ] Environmental Sciences, chemistry.chemical_compound, Mire, medicine, Tropospheric ozone, Testate amoebae, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, media_common, Ecology, 04 agricultural and veterinary sciences, 15. Life on land, [ SDE.MCG ] Environmental Sciences/Global Changes, chemistry, 13. Climate action, [SDE]Environmental Sciences, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries, Environmental science, Terrestrial ecosystem
Abstract: Tropospheric ozone pollution is recognised as an important threat to terrestrial ecosystems but impacts on peatlands are little understood despite the importance of peat as a global carbon store. Here we investigate the impacts of three levels of elevated exposure to tropospheric ozone on peatland microbial communities with a particular focus on testate amoebae, the dominant microbial consumers. We found that in the intermediate (ambient + 25 ppb O3) and high treatments (ambient +35 ppb summer, +10 ppb year round) there were significant changes in testate amoeba communities, typified by an increase in abundance of Phyrganella spp. and loss of diversity. Phyrganella is often suggested to feed on fungi so the community change identified in our experiment might suggest that the testate amoeba response is at least partially mediated by interactions with other microbial groups. We do not find evidence for changes in numbers of undifferentiated microalgae, nematodes or rotifers but do find weak evidence for an increase in flagellates and ciliates. Our results provide the first direct data to show the impact of ozone on microbial consumers in peatlands.
Published: 2017
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23. Tipping point in plant-fungal interactions under severe drought causes abrupt rise in peatland ecosystem respiration

Author: Mariusz Lamentowicz, Edward A. D. Mitchell, Pierre Mariotte, Monika Reczuga, Luca Bragazza, Sandra Słowińska, Małgorzata Zielińska, Bogdan H. Chojnicki, Jan Barabach, Christophe V. W. Seppey, Enrique Lara, Alexandre Buttler, Michał Słowiński, Vincent E. J. Jassey, Bjorn J. M. Robroek, Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratory of Wetland Ecology and Monitoring, Faculty of Geographical and Geological Sciences, Adam Mickiewicz University, Department of Geoecology and Climatology, Institute of Geography and Spatial Organization, Polska Akademia Nauk = Polish Academy of Sciences (PAN), Laboratoire des systèmes écologiques (ECOS), Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratory of Soil Biology, Université de Neuchâtel (UNINE), Faculty of Environment Engineering and Spatial Management, Department of Meteorology, Poznan University of Life Sciences, Adam Mickiewicz University in Poznań (UAM), and Polish Academy of Sciences
Subjects: 0106 biological sciences, Peat, 010504 meteorology & atmospheric sciences, Water table, 01 natural sciences, Sink (geography), Dissolved organic carbon, threshold, moving window structural equation model, Groundwater, Soil Microbiology, ComputingMilieux_MISCELLANEOUS, General Environmental Science, VDP::Mathematics and natural science: 400, biodiversity–ecosystem functioning, Global and Planetary Change, geography.geographical_feature_category, Ecology, food and beverages, plant–soil feedbacks, Plants, biodiversity–ecosystem functioning, ecosystem shifts, fungal diversity, hydrolases, moving window structural equation model, oxidases, plant–soil feedbacks, threshold, Droughts, oxidases, Ecosystem respiration, Cycling, Climate Change, [SDE.MCG]Environmental Sciences/Global Changes, hydrolases, 010603 evolutionary biology, Oxygen Consumption, ecosystem shifts, Environmental Chemistry, Ecosystem, Symbiosis, 0105 earth and related environmental sciences, geography, fungi, Fungi, technology, industry, and agriculture, Ambientale, Water, VDP::Matematikk og Naturvitenskap: 400, 15. Life on land, Water level, fungal diversity, 13. Climate action, Wetlands, Environmental science
Abstract: This is the peer reviewed version of the following article: Jassey, V. E. J., Reczuga, M. K., Zielinska, M., Slowinska, S., Robroek, B. J. M., Mariotte, P., ... Buttler, A. (2017) Tipping point in plant–fungal interactions under severe drought causes abrupt rise in peatland ecosystem respiration. Global Change Biology, 24(3), 972-98., which has been published in final form at https://doi.org/10.1111/gcb.13928. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. Ecosystems are increasingly prone to climate extremes, such as drought, with long‐lasting effects on both plant and soil communities and, subsequently, on carbon (C) cycling. However, recent studies underlined the strong variability in ecosystem's response to droughts, raising the issue of nonlinear responses in plant and soil communities. The conundrum is what causes ecosystems to shift in response to drought. Here, we investigated the response of plant and soil fungi to drought of different intensities using a water table gradient in peatlands—a major C sink ecosystem. Using moving window structural equation models, we show that substantial changes in ecosystem respiration, plant and soil fungal communities occurred when the water level fell below a tipping point of −24 cm. As a corollary, ecosystem respiration was the greatest when graminoids and saprotrophic fungi became prevalent as a response to the extreme drought. Graminoids indirectly influenced fungal functional composition and soil enzyme activities through their direct effect on dissolved organic matter quality, while saprotrophic fungi directly influenced soil enzyme activities. In turn, increasing enzyme activities promoted ecosystem respiration. We show that functional transitions in ecosystem respiration critically depend on the degree of response of graminoids and saprotrophic fungi to drought. Our results represent a major advance in understanding the nonlinear nature of ecosystem properties to drought and pave the way towards a truly mechanistic understanding of the effects of drought on ecosystem processes.
Published: 2017
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24. Response to Editor to the comment by Delarue (2016) to our paper entitled ‘Persistent high temperature and low precipitation reduce peat carbon accumulation’

Author: Alexandre Buttler, Luca Bragazza, Vincent E. J. Jassey, Constant Signarbieux, Claudio Zaccone, Remy Albrecht, Bjorn J. M. Robroek, Laboratoire des systèmes écologiques (ECOS), Ecole Polytechnique Fédérale de Lausanne (EPFL), University of Southampton, Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), and Laboratory of Geographic Information Systems (LASIG), School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL)
Subjects: 0106 biological sciences, Peat, 010504 meteorology & atmospheric sciences, Web of science, Earth science, [SDE.MCG]Environmental Sciences/Global Changes, chemistry.chemical_element, 01 natural sciences, Carbon Cycle, Soil, Environmental Chemistry, Precipitation, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, General Environmental Science, Global and Planetary Change, Ecology, 010604 marine biology & hydrobiology, Temperature, Carbon, chemistry, 13. Climate action, Wetlands, [SDE]Environmental Sciences, Environmental science
Abstract: Reference EPFL-ARTICLE-226456doi:10.1111/gcb.13559View record in Web of Science Record created on 2017-03-13, modified on 2017-11-20
Published: 2017
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25. Always on the tipping point – A search for signals of past societies and related peatland ecosystem critical transitions during the last 6500 years in N Poland

Author: Edyta Łokas, Katarzyna Marcisz, Piotr Kołaczek, D. Mauquoy, Katarzyna Kajukało-Drygalska, Mariusz Lamentowicz, Michał Słowiński, Kamil Niedziółka, Vincent E. J. Jassey, Piotr Kittel, Department of Biogeography and Paleoecology, Adam Mickiewicz University in Poznań (UAM), Department of Environmental Resources and Geohazards, Institute of Geography and Spatial Organization, Polish Academy of Sciences, Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), and ANR-17-CE01-0007,MIXOPEAT,Repenser le cycle du carbone des tourbières : identifier le rôle des protistes mixotrophes dans la pompe à carbone biologique(2017)
Subjects: 010506 paleontology, Archeology, Global and Planetary Change, Peat, [SHS.ARCHEO]Humanities and Social Sciences/Archaeology and Prehistory, 010504 meteorology & atmospheric sciences, Library science, Geology, 15. Life on land, Tipping point (climatology), 01 natural sciences, Work (electrical), Agency (sociology), Ecosystem, ComputingMilieux_MISCELLANEOUS, Ecology, Evolution, Behavior and Systematics, Scientific activity, 0105 earth and related environmental sciences, Chronology
Abstract: The research was funded by a grant from the National Science Centre (Poland) (No 2015/17/B/ST10/01656). The work was also made in the framework of the National Programme of Development of Humanities project (No 2bH15015483) as well as budgetary sources for scientific activity in 2016–2019, project number 0342/IP1/2016/74. V.E.J.J. was supported by the French National Research Agency (MIXOPEAT project, grant number ANR-17-CE01–0007). We thank Julie Loisel help with the calculation of the peat carbon accumulation rates. We thank also Jerzy Sikora and Pawel Zawilski for defining the chronology of the potsherd found during field surveys in the Gleboczek vicinity, and Sambor Czerwinski for constructing the lidar terrain map of the study area.
Published: 2019
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26. Correction to ‘Unveiling tipping points in long-term ecological records from Sphagnum-dominated peatlands’

Author: Katarzyna Marcisz, Vincent E. J. Jassey, Mariusz Gałka, Katarzyna Kajukało-Drygalska, Mariusz Lamentowicz, Milva Druguet Dayras, and Michał Słowiński
Subjects: Peat, biology, Ecology, Special Feature, General Agricultural and Biological Sciences, biology.organism_classification, Agricultural and Biological Sciences (miscellaneous), Sphagnum, Term (time)
Abstract: Unveiling past tipping points is a prerequisite for a better understanding of how individual species and entire ecosystems will respond to future climate change. Such knowledge is key for the implementation of biodiversity conservation. We identify the relationships between peatland vegetation and hydrological conditions over the past 2000 years using plant macrofossils, testate amoebae-based quantitative hydrological reconstructions and Sphagnum-moss functional traits from seven Polish peatland records. Using threshold indicator taxa analysis, we discovered that plant community composition strongly converged at a water level of ca 11.7 cm, indicating a community-level tipping point. We identified 45 plant taxa that showed either an increase or a decrease in their relative abundance between 8 and 17 cm of water-level depth. Our analysis of Sphagnum community traits further showed that Sphagnum functional diversity was remarkably stable over time despite Sphagnum species sensitivity to hydrological conditions. Our results suggest that past hydrological shifts did not influence major functions of the Sphagnum community, such as photosynthetic capacity, growth and productivity, owing to species replacement with a similar functional space. Although further studies including trait plasticity will be required, our findings suggest that the capacity of the Sphagnum community to gain carbon remained stable despite hydrological changes.
Published: 2019
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27. Experimental climate warming alters the relationship between fungal root symbiosis and Sphagnum litter phenolics in two peatland microhabitats

Author: Soraya Rouifed, Marie-Laure Toussaint, Philippe Binet, Vincent E. J. Jassey, Geneviève Chiapusio, Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés ( LEHNA ), Institut National de la Recherche Agronomique ( INRA ) -Université Claude Bernard Lyon 1 ( UCBL ), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État ( ENTPE ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire Ecologie Fonctionnelle et Environnement - ECOLAB ( ECOLAB ), Institut National Polytechnique [Toulouse] ( INP ) -Université Paul Sabatier - Toulouse 3 ( UPS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ), ANR-07-VULN-0010,VULN,Impact du réchauffement climatique sur la focntion de puits de carbone de l'ecosysteme tourbières à sphaignes. ( 2007 ), Laboratoire Chrono-environnement - UFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés (LEHNA), Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE), Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, ANR-07-VULN-0010,VULN,Impact du réchauffement climatique sur la focntion de puits de carbone de l'ecosysteme tourbières à sphaignes.(2007), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), and ANR-07-VULN-0010,PEATWARM,Impact du réchauffement climatique sur la focntion de puits de carbone de l'ecosysteme tourbières à sphaignes.(2007)
Subjects: 0106 biological sciences, Peat, Soil Science, phenoloxidase, peroxidase, Dark septate endophyte, 01 natural sciences, Microbiology, Sphagnum, [ SDE ] Environmental Sciences, dark septate endophyte, Symbiosis, Botany, Ecosystem, bryophyte, Rhizosphere, biology, Ecology, Global warming, plant secondary metabolites (PSM), 04 agricultural and veterinary sciences, 15. Life on land, biology.organism_classification, 13. Climate action, ericoid mycorrhizae, [SDE]Environmental Sciences, 040103 agronomy & agriculture, Litter, 0401 agriculture, forestry, and fisheries, 010606 plant biology & botany
Abstract: International audience; Belowground interactions between plants and microorganisms are involved in numerous ecosystems processes such as carbon and nutrient cycling. Understanding their responses to on-going climate warming is thus of paramount importance to better predict future ecosystem functioning. We hypothesized that climate warming alters the interactions between Sphagnum litter phenolics and the fungal root symbiosis of the Ericale plant Andromeda polifolia in a Jura mountain peatland (France). We initiate a climate warming treatment (+1°C) in April 2008 in two microhabitats (lawns and hummocks). We measured polyphenolic contents, mycorrhizal and dark septate endophyte (DSE) root colonization, phenoloxidase and peroxidase activities in the A. polifolia rhizosphere from 2010 to 2012. We found that four years of warming modulated rhizospheric parameters (fungal root symbiosis and enzyme activities) of A. polifolia, but the response differed between microhabitats. Enzyme activities and fungal root colonization displayed different responses to warming according to the microhabitats. DSE root colonization increased and peroxidase activities decreased in warmed Hummocks while they remained stable in warmed lawns. We found a significant positive correlation between DSE root colonization and litter phenolics recovered in both microhabitats but only under in ambient conditions. On the contrary, significant negative correlation was observed between mycorrhizae and litter phenolics recovered in warmed plots while no relationship was found in control plots. Our work thus provides evidences that interplay between phenolics from Sphagnum litter and fungal symbiosis of an Ericale species in peatlands was affected by climate warming. It highlights different plant biological responses to climate warming according to peatland microhabitats and confirm that belowground activities are crucial to understand the response of peatlands to climate change.
Published: 2017
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28. Taxonomic and functional turnover are decoupled in European peat bogs

Author: Magalí Martí, Nancy B. Dise, Simon J.M. Caporn, Bjorn J. M. Robroek, Katarzyna Zając, Jasper van Ruijven, Vincent E. J. Jassey, Jens Kattge, Richard J. Payne, Bo H. Svensson, Albert Bleeker, Luca Bragazza, Alexandre Buttler, Jos T. A. Verhoeven, Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Department of Environmental & Geographical Sciences, Manchester Metropolitan University (MMU), Max Planck Institute for Biogeochemistry (MPI-BGC), Max-Planck-Gesellschaft, Ecology and Biodiversity, Departement of Biology, Utrecht University [Utrecht], Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université de Toulouse (UT)
Subjects: 0106 biological sciences, Peat, 010504 meteorology & atmospheric sciences, Environmental change, Naturgeografi, Biodiversity, General Physics and Astronomy, Wetland, 01 natural sciences, Soil, Cluster Analysis, lcsh:Science, Principal Component Analysis, Multidisciplinary, geography.geographical_feature_category, Geography, Ecology, Vegetation, Plants, PE&RC, Europe, Plantenecologie en Natuurbeheer, Ecosystem ecology, Science, Plant Ecology and Nature Conservation, Environment, Biology, 010603 evolutionary biology, Article, General Biochemistry, Genetics and Molecular Biology, Ecology and Environment, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, Sphagnopsida, Life Science, Ecosystem, 0105 earth and related environmental sciences, geography, Ambientale, Plant community, General Chemistry, 15. Life on land, Carbon, Physical Geography, Wetlands, Linear Models, lcsh:Q, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract: In peatland ecosystems, plant communities mediate a globally significant carbon store. The effects of global environmental change on plant assemblages are expected to be a factor in determining how ecosystem functions such as carbon uptake will respond. Using vegetation data from 56 Sphagnum-dominated peat bogs across Europe, we show that in these ecosystems plant species aggregate into two major clusters that are each defined by shared response to environmental conditions. Across environmental gradients, we find significant taxonomic turnover in both clusters. However, functional identity and functional redundancy of the community as a whole remain unchanged. This strongly suggests that in peat bogs, species turnover across environmental gradients is restricted to functionally similar species. Our results demonstrate that plant taxonomic and functional turnover are decoupled, which may allow these peat bogs to maintain ecosystem functioning when subject to future environmental change., Peatland plant communities are expected to be affected by environmental change, though how assemblages respond is not fully understood. Here, Robroek et al. show that peatland species occur in two distinct clusters, and functional identity and redundancy was maintained under taxonomic turnover.
Published: 2017
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29. A novel testate amoebae trait-based approach to infer environmental disturbance in Sphagnum peatlands

Author: Willy Tinner, Mariusz Lamentowicz, Mariusz Gałka, Daniele Colombaroli, Monika Karpińska-Kołaczek, Katarzyna Marcisz, Vincent E. J. Jassey, Piotr Kołaczek, Michał Słowiński, Laboratory of Wetland Ecology and Monitoring, Faculty of Geographical and Geological Sciences, Adam Mickiewicz University in Poznań (UAM), Institute of Plant Sciences, University of Bern, Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Oeschger Centre for Climate Change Research (OCCR), Institute of Geoecology and Geoinformation, Institute of Physics [Toruń], Faculty of Physics, Astronomy and Informatics [Toruń], Nicolaus Copernicus University [Toruń]-Nicolaus Copernicus University [Toruń], Laboratory of Wetland Ecology and Monitoring, and Faculty of Geographical and Geological Sciences, Adam Mickiewicz University
Subjects: 0106 biological sciences, Multidisciplinary, Peat, 010504 meteorology & atmospheric sciences, biology, Ecology, [SDE.MCG]Environmental Sciences/Global Changes, Trait based, Community structure, 580 Plants (Botany), 15. Life on land, biology.organism_classification, 010603 evolutionary biology, 01 natural sciences, Sphagnum, Article, Trait, Paleoecology, Ecosystem, Testate amoebae, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: Species’ functional traits are closely related to ecosystem processes through evolutionary adaptation, and are thus directly connected to environmental changes. Species’ traits are not commonly used in palaeoecology, even though they offer powerful advantages in understanding the impact of environmental disturbances in a mechanistic way over time. Here we show that functional traits of testate amoebae (TA), a common group of palaeoecological indicators, can serve as an early warning signal of ecosystem disturbance and help determine thresholds of ecosystem resilience to disturbances in peatlands. We analysed TA traits from two Sphagnum-dominated mires, which had experienced different kinds of disturbances in the past 2000 years – fire and peat extraction, respectively. We tested the effect of disturbances on the linkages between TA community structure, functional trait composition and functional diversity using structural equation modelling. We found that traits such as mixotrophy and small hidden apertures (plagiostomic apertures) are strongly connected with disturbance, suggesting that these two traits can be used as palaeoecological proxies of peatland disturbance. We show that TA functional traits may serve as a good proxy of past environmental changes, and further analysis of trait-ecosystem relationships could make them valuable indicators of the contemporary ecosystem state.
Published: 2016
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30. Experimental climate effect on seasonal variability of polyphenol/phenoloxidase interplay along a narrow fen-bog ecological gradient in Sphagnum fallax

Author: Vincent E. J. Jassey, Philippe Binet, Daniel Gilbert, Geneviève Chiapusio, Alexandre Buttler, and Marei-Laure Toussaint
Subjects: 0106 biological sciences, Peat, Growing season, 010603 evolutionary biology, 01 natural sciences, Carbon cycle, Environmental Chemistry, Ecosystem, Bog, General Environmental Science, Global and Planetary Change, geography, geography.geographical_feature_category, Ecology, biology, Chemistry, Global warming, 04 agricultural and veterinary sciences, Soil carbon, 15. Life on land, biology.organism_classification, Sphagnum fallax, 13. Climate action, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries
Abstract: Extracellular phenoloxidase enzymes play an important role in the stability of soil carbon storage by contributing to the cycling of complex recalcitrant phenolic compounds. Climate warming could affect peatland functioning through an alteration of polyphenol/phenoloxidase interplay, which could lead them to becoming weaker sinks of carbon. Here, we assessed the seasonal variability of total phenolics and phenoloxidases subjected to 2-3 degrees C increase in air temperature using open-top chambers. The measurements were performed along a narrow fen-bog ecological gradient over one growing season. Climate warming had a weak effect on phenoloxidases, but reduced phenolics in both fen and bog areas. Multivariate analyses revealed a split between the areas and also showed that climate warming exacerbated the seasonal variability of polyphenols, culminating in a destabilization of the carbon cycle. A negative relationship between polyphenols and phenoloxidases was recorded in controls and climate treatments suggesting an inhibitory effect of phenolics on phenoloxidases. Any significant decrease of phenolics through repeatedly elevated temperature would greatly impact the ecosystem functioning and carbon cycle through an alteration of the interaction of polyphenols with microbial communities and the production of extracellular enzymes. Our climate treatments did not have the same impact along the fen-bog gradient and suggested that not all the peatland habitats would respond similarly to climate forcing.
Published: 2011
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31. Anthropogenic- and natural sources of dust in peatland during the Anthropocene

Author: Barbara Fiałkiewicz-Kozieł, Michał Słowiński, Piotr Kołaczek, Daniel Gilbert, Vincent E. J. Jassey, Elena D. Lapshina, Marina Frontasyeva, Beata Smieja-Król, K. Kaliszan, Alexandre Buttler, Mariusz Lamentowicz, Fatima Laggoun-Défarge, Katarzyna Marcisz, Department of Biogeography and Paleoecology, Adam Mickiewicz University in Poznań ( UAM ), Faculty of Earth Sciences, University of Silesia, Department of Neutron Activation Analysis, Frank Laboratory of Neutron Physics Joint Institute for Nuclear Research, Department of Environmental Resources and Geohazards, Institute of Geography and Spatial Organization, Polish Academy of Sciences, Yugra State University, Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Université de Franche-Comté ( UFC ) -Centre National de la Recherche Scientifique ( CNRS ), Swiss Federal Institute for Forest, Snow and Avalanche Research ( WSL ), Swiss Federal Institute for Forest, Snow and Avalanche Research WSL, Institut des Sciences de la Terre d'Orléans - UMR7327 ( ISTO ), Bureau de Recherches Géologiques et Minières (BRGM) ( BRGM ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université d'Orléans ( UO ) -Centre National de la Recherche Scientifique ( CNRS ), Biogéosystèmes Continentaux - UMR7327, Bureau de Recherches Géologiques et Minières (BRGM) ( BRGM ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université d'Orléans ( UO ) -Centre National de la Recherche Scientifique ( CNRS ) -Bureau de Recherches Géologiques et Minières (BRGM) ( BRGM ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université d'Orléans ( UO ) -Centre National de la Recherche Scientifique ( CNRS ), grant 2011/01/D/ST10/02579 from the Polish National Centre of Science (NCN) (PI:Barbara Fiałkiewicz-Kozieł). We acknowledge the support of the International Network for Terrestrial Researchand Monitoring in the Arctic (INTERACT) that funded the project: 'Functioning of Siberian mire ecosystemsand their response to climate changes' (CliMireSiber) (PI: Fatima Laggoun-Defarge) and Grant PSPB-013/2010through the Swiss Contribution to the enlarged European Union (CLIMPEAT, www.climpeat.pl) (PI: MariuszLamentowicz). This study is a contribution to the Virtual Institute of Integrated Climate and Landscape Evolution(ICLEA) of the Helmholtz Association and Science and Research Funds for 2015–2016, allocated to a co-financedinternational project (No. 3500/ICLEA/15/2016/0)., Adam Mickiewicz University in Poznań (UAM), Faculty of Earth Sciences, University of Silesia, University of Silesia in Katowice, Frank Laboratory of Neutron Physics [Dubna] (FLNP), Joint Institute for Nuclear Research (JINR)-Joint Institute for Nuclear Research (JINR), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC)
Subjects: Peat, 010504 meteorology & atmospheric sciences, Earth science, 010502 geochemistry & geophysics, dust sources, 01 natural sciences, Natural (archaeology), Article, Atmosphere, Soil, Anthropocene, [ SDU.ENVI ] Sciences of the Universe [physics]/Continental interfaces, environment, Humans, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Western siberia, 0105 earth and related environmental sciences, Multidisciplinary, Ecology, Dust, Anthropogenic sources, Siberia, Deposition (aerosol physics), 13. Climate action, [SDU]Sciences of the Universe [physics], Anthropology, Environmental science, [ SDU ] Sciences of the Universe [physics], Dust emission
Abstract: As human impact have been increasing strongly over the last decades, it is crucial to distinguish human-induced dust sources from natural ones in order to define the boundary of a newly proposed epoch - the Anthropocene. Here, we track anthropogenic signatures and natural geochemical anomalies in the Mukhrino peatland, Western Siberia. Human activity was recorded there from cal AD 1958 (±6). Anthropogenic spheroidal aluminosilicates clearly identify the beginning of industrial development and are proposed as a new indicator of the Anthropocene. In cal AD 1963 (±5), greatly elevated dust deposition and an increase in REE serve to show that the geochemistry of elements in the peat can be evidence of nuclear weapon testing; such constituted an enormous force blowing soil dust into the atmosphere. Among the natural dust sources, minor signals of dryness and of the Tunguska cosmic body (TCB) impact were noted. The TCB impact was indirectly confirmed by an unusual occurrence of mullite in the peat.
Published: 2016
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32. Persistent high temperature and low precipitation reduce peat carbon accumulation

Author: Luca Bragazza, Remy Albrecht, Alexandre Buttler, Bjorn J. M. Robroek, Constant Signarbieux, Claudio Zaccone, Vincent E. J. Jassey, Laboratoire des systèmes écologiques (ECOS), Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), and Laboratory of Geographic Information Systems (LASIG), School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL)
Subjects: Biogeochemical cycle, Peat, 010504 meteorology & atmospheric sciences, Q10, carbon accumulation, climate extreme, drought, organic matter chemistry, plant productivity, soil enzymes, soil respiration, [SDE.MCG]Environmental Sciences/Global Changes, carbon accumulation, climate extreme, drought, organic matter chemistry, plant productivity, Q10, soil enzymes, soil respiration, 01 natural sciences, Carbon cycle, Soil respiration, Environmental Chemistry, Ecosystem, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, General Environmental Science, Global and Planetary Change, Ecology, Ambientale, 04 agricultural and veterinary sciences, Soil carbon, 15. Life on land, (10), Transplantation, Agronomy, 13. Climate action, Soil water, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries, Environmental science
Abstract: Extreme climate events are predicted to become more frequent and intense. Their ecological impacts, particularly on carbon cycling, can differ in relation to ecosystem sensitivity. Peatlands, being characterized by peat accumulation under waterlogged conditions, can be particularly sensitive to climate extremes if the climate event increases soil oxygenation. However, a mechanistic understanding of peatland responses to persistent climate extremes is still lacking, particularly in terms of aboveground-belowground feedback. Here, we present the results of a transplantation experiment of peat mesocosms from high to low altitude in order to simulate, during 3years, a mean annual temperature c. 5 degrees C higher and a mean annual precipitation c. 60% lower. Specifically, we aim at understanding the intensity of changes for a set of biogeochemical processes and their feedback on carbon accumulation. In the transplanted mesocosms, plant productivity showed a species-specific response depending on plant growth forms, with a significant decrease (c. 60%) in peat moss productivity. Soil respiration almost doubled and Q(10) halved in the transplanted mesocosms in combination with an increase in activity of soil enzymes. Spectroscopic characterization of peat chemistry in the transplanted mesocosms confirmed the deepening of soil oxygenation which, in turn, stimulated microbial decomposition. After 3years, soil carbon stock increased only in the control mesocosms whereas a reduction in mean annual carbon accumulation of c. 30% was observed in the transplanted mesocosms. Based on the above information, a structural equationmodel was built to provide a mechanistic understanding of the causal connections between peat moisture, vegetation response, soil respiration and carbon accumulation. This study identifies, in the feedback between plant and microbial responses, the primary pathways explaining the reduction in carbon accumulation in response to recurring climate extremes in peat soils.
Published: 2016
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33. An unexpected role for mixotrophs in the response of peatland carbon cycling to climate warming

Author: Bertrand Fournier, Luca Bragazza, Stephan Hättenschwiler, Alexandre Buttler, Bjorn J. M. Robroek, Frédéric Delarue, Constant Signarbieux, Richard J. Payne, Daniel Gilbert, Edward A. D. Mitchell, Fatima Laggoun-Défarge, Enrique Lara, Vincent E. J. Jassey, Robert T. E. Mills, Swiss Federal Institute for Forest, Snow and Avalanche Research WSL, School of Architecture, Civil and Environmental Engineering ( ENAC ), Ecole Polytechnique Fédérale de Lausanne ( EPFL ), Centre d’Ecologie Fonctionnelle et Evolutive ( CEFE ), Université Paul-Valéry - Montpellier 3 ( UM3 ) -Centre international d'études supérieures en sciences agronomiques ( Montpellier SupAgro ) -École pratique des hautes études ( EPHE ) -Institut national de la recherche agronomique [Montpellier] ( INRA Montpellier ) -Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut de Recherche pour le Développement ( IRD [France-Sud] ) -Institut national d’études supérieures agronomiques de Montpellier ( Montpellier SupAgro ), University of Ferrara [Ferrara], Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Université de Franche-Comté ( UFC ) -Centre National de la Recherche Scientifique ( CNRS ), Institut des Sciences de la Terre d'Orléans - UMR7327 ( ISTO ), Bureau de Recherches Géologiques et Minières (BRGM) ( BRGM ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université d'Orléans ( UO ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire de biodiversité du sol [Neuchâtel], Université de Neuchâtel, WSL Lausanne, WSL, Centre des Sciences du Goût et de l'Alimentation [Dijon] ( CSGA ), Institut National de la Recherche Agronomique ( INRA ) -Université de Bourgogne ( UB ) -AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Centre National de la Recherche Scientifique ( CNRS ), Jardin Botanique de Neuchâtel, Institute of Biology - Laboratory of Soil Biology, Manchester Metropolitan University ( MMU ), Polish Ministry of Science and Higher Education (grant NN305077936),through the Swiss Contribution to the enlarged European Union (Climpeat project, PSPB-013/2010).Russian Scientific Fund (Grant 14-14-00891)., ANR-07-VULN-0010,PEATWARM,Impact du réchauffement climatique sur la focntion de puits de carbone de l'ecosysteme tourbières à sphaignes. ( 2007 ), Swiss Federal Institute for Forest, Snow and Landscape Research WSL, School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre d’Ecologie Fonctionnelle et Evolutive (CEFE), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Institut National de la Recherche Agronomique (INRA)-Université Paul-Valéry - Montpellier 3 (UPVM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut de Recherche pour le Développement (IRD [France-Sud]), Università degli Studi di Ferrara (UniFE), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Université de Neuchâtel (UNINE), Manchester Metropolitan University (MMU), ANR-07-VULN-0010,PEATWARM,Impact du réchauffement climatique sur la focntion de puits de carbone de l'ecosysteme tourbières à sphaignes.(2007), Université Paul-Valéry - Montpellier 3 (UM3)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-École pratique des hautes études (EPHE)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Laboratoire Chrono-environnement - UFC (UMR 6249) (LCE), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Université Paul-Valéry - Montpellier 3 (UPVM)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Università degli Studi di Ferrara = University of Ferrara (UniFE), Laboratoire Chrono-environnement (UMR 6249) (LCE), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Peat, 010504 meteorology & atmospheric sciences, Climate Change, 01 natural sciences, Sphagnum, Article, Decomposer, Carbon Cycle, Carbon cycle, 03 medical and health sciences, Sphagnopsida, [ SDU.ENVI ] Sciences of the Universe [physics]/Continental interfaces, environment, Ecosystem, Biomass, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, 030304 developmental biology, 0105 earth and related environmental sciences, 0303 health sciences, Biomass (ecology), Multidisciplinary, Bacteria, Phototroph, biology, Ecology, Fungi, Ambientale, Carbon Dioxide, 15. Life on land, biology.organism_classification, Carbon, [SDU]Sciences of the Universe [physics], 13. Climate action, Energy Metabolism, Microcosm, [ SDU ] Sciences of the Universe [physics]
Abstract: International audience; Mixotrophic protists are increasingly recognized for their significant contribution to carbon (C) cycling. As phototrophs they contribute to photosynthetic C fixation, whilst as predators of decomposers, they indirectly influence organic matter decomposition. Despite these direct and indirect effects on the C cycle, little is known about the responses of peatland mixotrophs to climate change and the potential consequences for the peatland C cycle. With a combination of field and microcosm experiments, we show that mixotrophs in the Sphagnum bryosphere play an important role in modulating peatland C cycle responses to experimental warming. We found that five years of consecutive summer warming with peaks of �2 to +8°C led to a 50% reduction in the biomass of the dominant mixotrophs, the mixotrophic testate amoebae (MTA). The biomass of other microbial groups (including decomposers) did not change, suggesting MTA to be particularly sensitive to temperature. In a microcosm experiment under controlled conditions, we then manipulated the abundance of MTA, and showed that the reported 50% reduction of MTA biomass in the field was linked to a significant reduction of net C uptake (-13%) of the entire Sphagnum bryosphere. Our findings suggest that reduced abundance of MTA with climate warming could lead to reduced peatland C fixation. The vast majority of the Earth's organisms meet their requirements for carbon (C) and energy either by utilising light to assimilate CO 2 through photosynthesis (autotrophy), or by the uptake of organic C compounds (heterotrophy). However, some organisms have the potential to combine auto-and heterotrophic C uptake, a strategy termed 'mixotrophy'
Published: 2015
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34. Hydrological dynamics and fire history of the last 1300years in western Siberia reconstructed from a high-resolution, ombrotrophic peat archive

Author: Alexandre Buttler, Karolina Kaliszan, Vincent E. J. Jassey, Daniel Gilbert, Elena D. Lapshina, Piotr Kołaczek, Katarzyna Marcisz, Barbara Fiałkiewicz-Kozieł, Michał Słowiński, Mariusz Lamentowicz, Fatima Laggoun-Défarge, Małgorzata Zielińska, Laboratory of Wetland Ecology and Monitoring, Faculty of Geographical and Geological Sciences, Adam Mickiewicz University, Department of Biogeography and Paleoecology, Adam Mickiewicz University in Poznań (UAM), German Research Centre for Geosciences - Helmholtz-Centre Potsdam (GFZ), Department of Environmental Resources and Geohazards, Institute of Geography and Spatial Organization, Polish Academy of Sciences, Yugra State University, Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Swiss Federal Institute for Forest, Snow and Landscape Research WSL, ÉcolePolytechniqueFédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), RE-FIRE SCIEX project 12.286 and grant PSPB-013/2010 from Switzerland through the Swiss Contribution to the enlarged European Union, as well as by grant 2011/01/D/ST10/02579 from the National Centre of Science (NCN)., International Network for Terrestrial Research and Monitoring in the Arctic INTERACT that funded the project: 'Functioning of Siberian mire ecosystems and their response to climate changes' Project acronym: CliMireSiber (PI: Fatima Laggoun-Defarge)., Adam Mickiewicz University in Poznań ( UAM ), German Research Centre for Geosciences - Helmholtz-Centre Potsdam ( GFZ ), Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Swiss Federal Institute for Forest, Snow and Avalanche Research WSL, Institut des Sciences de la Terre d'Orléans - UMR7327 ( ISTO ), and Bureau de Recherches Géologiques et Minières (BRGM) ( BRGM ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université d'Orléans ( UO ) -Centre National de la Recherche Scientifique ( CNRS )
Subjects: 010506 paleontology, Peat,  Testate amoebae, 010504 meteorology & atmospheric sciences, Environmental change, Ombrotrophic, 01 natural sciences, Arts and Humanities (miscellaneous), Mire, [ SDU.ENVI ] Sciences of the Universe [physics]/Continental interfaces, environment, Testate amoebae, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, 0105 earth and related environmental sciences, Earth-Surface Processes, Macrofossils, Ecology, Transfer function, Macrofossil, Vegetation, 15. Life on land, Siberia, Arctic oscillation, 13. Climate action, [SDU]Sciences of the Universe [physics], Charcoal, General Earth and Planetary Sciences, Pollen, Physical geography, [ SDU ] Sciences of the Universe [physics], Geology
Abstract: International audience; Siberian peatlands provide records of past changes in the continental climate of Eurasia. We analyzed a core from Mukhrino mire in western Siberia to reconstruct environmental change in this region over the last 1300 years. The pollen analysis revealed little variation of local pine-birch forests. A testate amoebae transfer function was used to generate a quantitative water-table reconstruction; pollen, plant macrofossils, and charcoal were analyzed to reconstruct changes in vegetation and fire activity. The study revealed that Mukhrino mire was wet until the Little Ice Age (LIA), when drought was recorded. Dry conditions during the LIA are consistent with other studies from central and eastern Europe, and with the pattern of carbon accumulation across the Northern Hemisphere. A significant increase in fire activity between ca. AD 1975 and 1990 may be associated with the development of the nearby city of Khanty-Mansiysk, as well as with the prevailing positive Arctic Oscillation.
Published: 2015
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35. Loss of testate amoeba functional diversity with increasing frost intensity across a continental gradient reduces microbial activity in peatlands

Author: Robert T. E. Mills, Bjorn J. M. Robroek, Maaike L. Hofsommer, Vincent E. J. Jassey, Luca Bragazza, Alexandre Buttler, Mariusz Lamentowicz, Constant Signarbieux, Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratory of Wetland Ecology and Monitoring, Faculty of Geographical and Geological Sciences, Adam Mickiewicz University, Laboratoire des systèmes écologiques (ECOS), Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Federal Institute for Forest, Snow and Landscape Research WSL, and Laboratory of Geographic Information Systems (LASIG), School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL)
Subjects: 0106 biological sciences, Peat, Osmotic shock, [SDE.MCG]Environmental Sciences/Global Changes, Beta diversity, Climate change, Growing season, Functional turnover, Biology, 010603 evolutionary biology, 01 natural sciences, Microbiology, Soil, Nutrient, Freezing, Testate amoebae, Amoeba, Mixotrophy, ComputingMilieux_MISCELLANEOUS, Enzymatic activity, Ecology, 010604 marine biology & hydrobiology, Ambientale, Beta-diversity, Biodiversity, 15. Life on land, Phenolic compounds, Winter climate change, 13. Climate action, Wetlands, Mixotroph
Abstract: Soil microbial communities significantly contribute to global fluxes of nutrients and carbon. Their response to climate change, including winter warming, is expected to modify these processes through direct effects on microbial functions due to osmotic stress, and changing temperature regimes. Using four European peatlands reflecting different frequencies of frost events, we show that peatland testate amoeba communities diverge among sites with different winter climates, and that this is reflected through contrasting functions. We found that exposure to harder soil frost promoted species (3-diversity (species turnover) thus shifting the community composition of testate amoebae. In particular, we found that harder soil frost, and lower water-soluble phenolic compounds, induced functional turnover through the decrease of large species (-68%, >80 mu m) and the increase of small-bodied mixotrophic species (i.e. Archerella flavum; +79%). These results suggest that increased exposure to soil frost could be highly limiting for large species while smaller species are more resistant. Furthermore, we found that beta-glucosidase enzymatic activity, in addition to soil temperature, strongly depended of the functional diversity of testate amoebae (R-2 = 0.95, ANOVA). Changing winter conditions can therefore strongly impact peatland decomposition process, though it remains unclear if these changes are carried-over to the growing season. (C) 2016 Elsevier GmbH. All rights reserved.
Published: 2015
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36. Experimental warming differentially affects microbial structure and activity in two contrasted moisture sites in a Sphagnum-dominated peatland

Author: Alexandre Buttler, Luca Bragazza, Laurent Grasset, Fatima Laggoun-Défarge, Frédéric Delarue, Vincent E. J. Jassey, Sébastien Gogo, Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Institut Fédéral de Recherches sur la Forêt, la Neige et le Paysage (WSL), Institut Fédéral de Recherches [Suisse], Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), CMCS-EPFL (CMCS-EPFL), Ecole Polytechnique Fédérale de Lausanne (EPFL), Biology and Evolution, University of Ferrara, Università degli Studi di Ferrara (UniFE), Synthèse et réactivité des substances naturelles (SRSN), Université de Poitiers-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), ANR-07-VULN-0010,PEATWARM,Impact du réchauffement climatique sur la focntion de puits de carbone de l'ecosysteme tourbières à sphaignes.(2007), ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Chrono-environnement - UFC (UMR 6249) (LCE), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), University of Ferrara [Ferrara], Université de Poitiers-Centre National de la Recherche Scientifique (CNRS), ANR-10-LABX-100-01/10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), Institut des Sciences de la Terre d'Orléans - UMR7327 ( ISTO ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Bureau de Recherches Géologiques et Minières (BRGM) ( BRGM ) -Université d'Orléans ( UO ) -Centre National de la Recherche Scientifique ( CNRS ), Institut Fédéral de Recherches sur la Forêt, la Neige et le Paysage ( WSL ), Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), CMCS-EPFL ( CMCS-EPFL ), Ecole Polytechnique Fédérale de Lausanne ( EPFL ), Synthèse et réactivité des substances naturelles ( SRSN ), Université de Poitiers-Centre National de la Recherche Scientifique ( CNRS ), ANR-07-VULN-0010,PEATWARM,Impact du réchauffement climatique sur la focntion de puits de carbone de l'ecosysteme tourbières à sphaignes. ( 2007 ), ANR-10-LABX-100-01/10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment ( 2010 ), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)
Subjects: Environmental Engineering, Peat, 010504 meteorology & atmospheric sciences, Microbial biomass, 01 natural sciences, Sphagnum, Soil, Carbon Climate change Enzymes Microbial biomass Moisture Open-top chambers, Sphagnopsida, [ SDU.ENVI ] Sciences of the Universe [physics]/Continental interfaces, environment, Environmental Chemistry, Climate change, Organic matter, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Waste Management and Disposal, Water content, Bog, Ecosystem, Soil Microbiology, Moisture, 0105 earth and related environmental sciences, chemistry.chemical_classification, Biomass (ecology), geography, geography.geographical_feature_category, biology, Open-top chambers, Ecology, Global warming, Temperature, 04 agricultural and veterinary sciences, 15. Life on land, biology.organism_classification, Pollution, Carbon, Enzymes, chemistry, 13. Climate action, Environmental chemistry, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries, Environmental science
Abstract: Several studies on the impact of climate warming have indicated that peat decomposition/mineralization will be enhanced. Most of these studies deal with the impact of experimental warming during summer when prevalent abiotic conditions are favorable to decomposition. Here, we investigated the effect of experimental air warming by open-top chambers (OTCs) on water-extractable organic matter (WEOM), microbial biomasses and enzymatic activities in two contrasted moisture sites named Bog and Fen sites, the latter considered as the wetter ones. While no or few changes in peat temperature and water content appeared under the overall effect of OTCs, we observed that air warming smoothed water content differences and led to a decrease in mean peat temperature at the warmed Bog sites. This thermal discrepancy between the two sites led to contrasting changes in microbial structure and activities: a rise in hydrolytic activity at the warmed Bog sites and a relative enhancement of bacterial biomass at the warmed Fen sites. These features were not associated with any change in WEOM properties namely carbon and sugar contents and aromaticity, suggesting that air warming did not trigger any shift in OM decomposition. Using various tools, we show that the use of single indicators of OM decomposition can lead to fallacious conclusions. Lastly, these patterns may change seasonally as a consequence of complex interactions between groundwater level and air warming, suggesting the need to improve our knowledge using a high time-resolution approach. (C) 2015 Elsevier B.V. All rights reserved.
Published: 2015
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37. Peatland vascular plant functional types affect methane dynamics by altering microbial community structure

Author: Vincent E. J. Jassey, Lauric Cécillon, Peter A. H. M. Bakker, Robert T. E. Mills, Roeland L. Berendsen, Paul L. E. Bodelier, Jeremy Puissant, Bjorn J. M. Robroek, Martine A. R. Kox, Marion Meima-Franke, Microbial Ecology (ME), Sub Plant-Microbe Interactions, Dep Biologie, Plant Microbe Interactions, UNIVERSITY OF UTRECHT NLD, Partenaires IRSTEA, Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Ecole Polytechnique Fédérale de Lausanne (EPFL), RADBOUD UNIVERSITY NIJMEGEN NLD, Ecosystèmes montagnards (UR EMGR), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), and Wageningen University and Research [Wageningen] (WUR)
Subjects: methanotrophic communities, Peat, 010504 meteorology & atmospheric sciences, Environmental change, plant-soil (below-ground) interactions, Methanogenesis, mid-infrared spectroscopy, Plant Science, phospholipid fatty acid, 01 natural sciences, Taverne, Organic matter, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, chemistry.chemical_classification, Abiotic component, Ecology, Atmospheric methane, methane, Plant community, 04 agricultural and veterinary sciences, methanogenesis, 15. Life on land, pathway analysis, Sphagnum-dominated peatlands, chemistry, Microbial population biology, 13. Climate action, Ecological Microbiology, international, [SDE]Environmental Sciences, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries, Environmental science, pmoA
Abstract: International audience; Peatlands are natural sources of atmospheric methane (CH4), an important greenhouse gas. It is established that peatland methane dynamics are controlled by both biotic and abiotic conditions, yet the interactive effect of these drivers is less studied and consequently poorly understood. Climate change affects the distribution of vascular plant functional types (PFTs) in peatlands. By removing specific PFTs, we assessed their effects on peat organic matter chemistry, microbial community composition and on potential methane production (PMP) and oxidation (PMO) in two microhabitats (lawns and hummocks). Whilst PFT removal only marginally altered the peat organic matter chemistry, we observed considerable changes in microbial community structure. This resulted in altered PMP and PMO. PMP was slightly lower when graminoids were removed, whilst PMO was highest in the absence of both vascular PFTs (graminoids and ericoids), but only in the hummocks. Path analyses demonstrate that different plant-soil interactions drive PMP and PMO in peatlands and that changes in biotic and abiotic factors can have auto-amplifying effects on current CH4 dynamics.Synthesis. Changing environmental conditions will, both directly and indirectly, affect peatland processes, causing unforeseen changes in CH4 dynamics. The resilience of peatland CH4 dynamics to environmental change therefore depends on the interaction between plant community composition and microbial communities.
Published: 2015
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38. Snow cover manipulation effects on microbial community structure and soil chemistry in a mountain bog

Author: Bjorn J. M. Robroek, T. Gerrit Rouwenhorst, Vincent E. J. Jassey, Alexandre Buttler, Luca Bragazza, Amber Heijboer, Mariet M. Hefting, University of Southampton, Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Utrecht University [Utrecht], Laboratoire des systèmes écologiques (ECOS), and Ecole Polytechnique Fédérale de Lausanne (EPFL)
Subjects: Peat, 010504 meteorology & atmospheric sciences, Plant Science, freeze-thaw cycles, 01 natural sciences, Wiskundige en Statistische Methoden - Biometris, nitrogen, Snow cover manipulation, Phospholipid fatty acids (PLFA), Bog, ComputingMilieux_MISCELLANEOUS, 2. Zero hunger, Biomass (ecology), geography.geographical_feature_category, Ecology, Soil chemistry, 04 agricultural and veterinary sciences, dynamics, PE&RC, Microbial communities, peatland, phosphatase activity, Winter Ecology, climate-change, [SDE]Environmental Sciences, rv-coefficient, Plantenecologie en Natuurbeheer, Phosphatase activity, trends, Peatland, [SDE.MCG]Environmental Sciences/Global Changes, Soil Science, Climate change, Plant Ecology and Nature Conservation, Temperate climate, Soil bacterial and fungal communities, Ecosystem, Mathematical and Statistical Methods - Biometris, 0105 earth and related environmental sciences, geography, biomass, tundra soils, variability, Biogeochemistry, 15. Life on land, forest soil, 13. Climate action, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries, Environmental science, human activities, Winter Ecology
Abstract: Background and Aims: Alterations in snow cover driven by climate change may impact ecosystem functioning, including biogeochemistry and soil (microbial) processes. We elucidated the effects of snow cover manipulation (SCM) on above-and belowground processes in a temperate peatland. Methods: In a Swiss mountain-peatland we manipulated snow cover (addition, removal and control), and assessed the effects on Andromeda polifolia root enzyme activity, soil microbial community structure, and leaf tissue and soil biogeochemistry. Results: Reduced snow cover produced warmer soils in our experiment while increased snow cover kept soil temperatures close-to-freezing. SCM had a major influence on the microbial community, and prolonged ‘close-to-freezing' temperatures caused a shift in microbial communities toward fungal dominance. Soil temperature largely explained soil microbial structure, while other descriptors such as root enzyme activity and pore-water chemistry interacted less with the soil microbial communities. Conclusions: We envisage that SCM-driven changes in the microbial community composition could lead to substantial changes in trophic fluxes and associated ecosystem processes. Hence, we need to improve our understanding on the impact of frost and freeze-thaw cycles on the microbial food web and its implications for peatland ecosystem processes in a changing climate; in particular for the fate of the sequestered carbon
Published: 2013
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39. Ammonia exposure promotes algal biomass in an ombrotrophic peatland

Author: Lucy J. Sheppard, Vincent E. J. Jassey, Ian D. Leith, Nancy B. Dise, Richard J. Payne, Daniel Gilbert, Manchester Metropolitan University ( MMU ), Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Centre for Ecology and Hydrology [Edinburgh] ( CEH ), Natural Environment Research Council ( NERC ), NERC Centre of Ecology and Hydrology ( CEH ), Department of Earth Sciences, The Open University [Milton Keynes] ( OU ), Department of Biology, Villanova University [Philadelphie], PRIMEQUAL, MICROPOLAIR, Manchester Metropolitan University (MMU), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Centre for Ecology and Hydrology [Edinburgh] (CEH), Natural Environment Research Council (NERC), NERC Centre of Ecology and Hydrology (CEH), School of Environment, Earth and Ecosystem Sciences [Milton Keynes], Faculty of Science, Technology, Engineering and Mathematics [Milton Keynes], The Open University [Milton Keynes] (OU)-The Open University [Milton Keynes] (OU), and Villanova University
Subjects: Nutrient cycle, Peat, Nitrogen, Soil Science, Ombrotrophic, Pollution impact, 010501 environmental sciences, 01 natural sciences, Microbiology, Euglenids, [ SDV.EE ] Life Sciences [q-bio]/Ecology, environment, Dominance (ecology), Ecosystem, Testate amoebae, 0105 earth and related environmental sciences, [SDV.EE]Life Sciences [q-bio]/Ecology, environment, Ecology, 04 agricultural and veterinary sciences, 15. Life on land, Bioindication, Desmids, Microbial population biology, 13. Climate action, Nutrient pollution, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries, Environmental science
Abstract: International audience; Nitrogen pollution affects many peatlands with consequences for their biodiversity and ecosystem function. Microorganisms control nutrient cycling and constitute most of the biodiversity of peatlands but their response to nitrogen is poorly characterised and likely to depend on the form of deposition. Using a unique field experiment we show that ammonia exposure at realistic point source levels is associated with a general shift from heterotrophic (bacteria and fungi) to autotrophic (algal) dominance and an increase in total biomass. The biomass of larger testate amoebae increased, suggesting increased food supply for microbial predators. Results show the widespread impacts of N pollution and suggest the potential for microbial community-based bioindicators in these ecosystems.
Published: 2013
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40. Above- and belowground linkages in Sphagnum peatland: climate warming affects plant-microbial interactions

Author: Edward A. D. Mitchell, Frédéric Delarue, André-Jean Francez, Fatima Laggoun-Défarge, Vincent E. J. Jassey, Geneviève Chiapusio, Alexandre Buttler, Nadine Bernard, Daniel Gilbert, Marie-Laure Toussaint, Philippe Binet, Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Institute of Biology - Laboratory of Soil Biology, Université de Neuchâtel (UNINE), Ecosystèmes, biodiversité, évolution [Rennes] (ECOBIO), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Université de Franche-Comté ( UFC ) -Centre National de la Recherche Scientifique ( CNRS ), Institut des Sciences de la Terre d'Orléans - UMR7327 ( ISTO ), Bureau de Recherches Géologiques et Minières (BRGM) ( BRGM ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université d'Orléans ( UO ) -Centre National de la Recherche Scientifique ( CNRS ), Université de Neuchâtel, Ecosystèmes, biodiversité, évolution [Rennes] ( ECOBIO ), Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -INEE-Observatoire des Sciences de l'Univers de Rennes ( OSUR ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire Chrono-environnement (UMR 6249) (LCE), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), and Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 0106 biological sciences, Nutrient cycle, Peat, water chemistry, [SDE.MCG]Environmental Sciences/Global Changes, food chains, 010603 evolutionary biology, 01 natural sciences, Sphagnum, Global Warming, microbial food web, Sphagnopsida, [ SDU.ENVI ] Sciences of the Universe [physics]/Continental interfaces, environment, Environmental Chemistry, Ecosystem, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, polyphenols, General Environmental Science, Global and Planetary Change, Microbial food web, Ecology, biology, Global warming, 04 agricultural and veterinary sciences, Soil carbon, 15. Life on land, biology.organism_classification, testate amoebae, [ SDE.MCG ] Environmental Sciences/Global Changes, plant and microbial communities, Microbial population biology, 13. Climate action, Host-Pathogen Interactions, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries, Environmental science
Abstract: International audience; Peatlands contain approximately one third of all soil organic carbon (SOC). Warming can alter above- and belowground linkages that regulate soil organic carbon dynamics and C-balance in peatlands. Here we examine the multiyear impact of in situ experimental warming on the microbial food web, vegetation, and their feedbacks with soil chemistry. We provide evidence of both positive and negative impacts of warming on specific microbial functional groups, leading to destabilization of the microbial food web. We observed a strong reduction (70%) in the biomass of top-predators (testate amoebae) in warmed plots. Such a loss caused a shortening of microbial food chains, which in turn stimulated microbial activity, leading to slight increases in levels of nutrients and labile C in water. We further show that warming altered the regulatory role of Sphagnum-polyphenols on microbial community structure with a potential inhibition of top predators. In addition, warming caused a decrease in Sphagnum cover and an increase in vascular plant cover. Using structural equation modelling, we show that changes in the microbial food web affected the relationships between plants, soil water chemistry, and microbial communities. These results suggest that warming will destabilize C and nutrient recycling of peatlands via changes in above- and belowground linkages, and therefore, the microbial food web associated with mosses will feedback positively to global warming by destabilizing the carbon cycle. This study confirms that microbial food webs thus constitute a key element in the functioning of peatland ecosystems. Their study can help understand how mosses, as ecosystem engineers, tightly regulate biogeochemical cycling and climate feedback in peatlands
Published: 2013
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41. Evidences of Bryophyte Allelochemical Interactions: The Case of Sphagnum

Author: M. Iftikhar Hussain, Geneviève Chiapusio, Vincent E. J. Jassey, and Philippe Binet
Subjects: 0106 biological sciences, Vascular plant, Peat, Ecology, 15. Life on land, Biology, biology.organism_classification, 010603 evolutionary biology, 01 natural sciences, Sphagnum, Sphagnum fallax, 13. Climate action, Germination, Botany, Terrestrial ecosystem, Bryophyte, Allelopathy, 010606 plant biology & botany
Abstract: In most terrestrial ecosystems, allelochemical interactions are involved in vascular plants. Nevertheless, bryophytes represent also a crucial group found in many ecosystems with a specific morphology and physiology (e.g. secondary metabolism). Among bryophytes, Sphagnum genus is of particular interest because they form a dense homogeneous carpet which is slowly decomposed (the peat) in peatlands. Such ecosystems represent a terrestrial sink of carbon and so are crucial to be studied, especially under a climate change. Objectives of this chapter were (1) to synthesize current bryophyte allelochemical interactions and (2) to illustrate recent research on Sphagnum with the case of Sphagnum fallax phenolics (production and degradation) recovered in a french peatland. The top layer of living Sphagnum represents the active allelopathic part where water-soluble phenolics were mostly recovered. Their concentrations were found to change along the seasons. The transformation of phenolic compounds is performed by an enzymatic system O2 (phenoloxidases) or H2O2 (peroxidases) dependent. Sphagnum-peroxidases constituted the main oxidative system and fungal phenoloxidases were proposed to be regulated by phenolics. Moreover, Sphagnum was able to regulate its secondary metabolism under a climate forcing by decreasing its phenolic concentrations. Allelopathic potential of Sphagnum phenolics was stated with their role in the microdistribution of associated Sphagnum microorganisms. Finally, Sphagnum extracts also strongly delayed Pine and Lolium germination seeds and inhibited Lolium radicle growth and delayed Raphanus and Pinus radicles. Ecological and agronomic perspectives of Sphagnum extracts are discussed.
Published: 2012
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42. Phenoloxidase and peroxidase activities in Sphagnum-dominated peatland in a warming climate

Author: Daniel Gilbert, Marie-Laure Toussaint, Philippe Binet, Geneviève Chiapusio, Vincent E. J. Jassey, Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), and Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)
Subjects: 0106 biological sciences, [SDV.EE]Life Sciences [q-bio]/Ecology, environment, Peat, biology, Ecology, Global warming, Soil Science, Lawn, 04 agricultural and veterinary sciences, Radiative forcing, biology.organism_classification, 01 natural sciences, Microbiology, Sphagnum, Carbon cycle, [ SDV.EE ] Life Sciences [q-bio]/Ecology, environment, 13. Climate action, Oxidative enzyme, 040103 agronomy & agriculture, biology.protein, 0401 agriculture, forestry, and fisheries, Environmental science, 010606 plant biology & botany, Peroxidase
Abstract: International audience; Peatlands still suffer from the scarcity of available data about the characterization and the response to climate forcing of the main oxidative enzymes that occur over the seasons. In the present study, phenoloxidase and peroxidase activities were examined in Sphagnum lawns along a narrow fen-bog gradient under experimental elevated temperatures. We showed that peroxidase activities from Sphagnum mosses were 1000-fold higher than those of phenoloxidases irrespective of seasons and sampling areas. Peroxidase activities increased (+30%) with the rise of air temperatures (an average of 1 °C), while warming did not alter phenoloxidase activities. These results suggest that the monitoring of peroxidase activities in peatlands may represent a suitable and forward indicator of the impact of climate warming on carbon cycle in peatlands.
Published: 2012

43. Fine-scale horizontal and vertical micro-distribution patterns of testate amoebae along a narrow Fen/Bog gradient

Author: Philippe Binet, Edward A. D. Mitchell, Daniel Gilbert, Vincent E. J. Jassey, Geneviève Chiapusio, Marie-Laure Toussaint, Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Laboratoire de biodiversité du sol [Neuchâtel], Université de Neuchâtel, Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), and Université de Neuchâtel (UNINE)
Subjects: 0106 biological sciences, Peat, Water table, Population Dynamics, Soil Science, 010603 evolutionary biology, 01 natural sciences, Sphagnum, [ SDV.EE ] Life Sciences [q-bio]/Ecology, environment, Phenols, Sphagnopsida, Testate amoebae, Amoeba, Bog, Ecology, Evolution, Behavior and Systematics, [SDV.EE]Life Sciences [q-bio]/Ecology, environment, geography, geography.geographical_feature_category, biology, Ecology, 010604 marine biology & hydrobiology, Temperature, Water, Biodiversity, 15. Life on land, biology.organism_classification, Sphagnum fallax, 13. Climate action, Wetlands, Paleoecology, Poor fen, France
Abstract: The ecology of peatland testate amoebae is well studied along broad gradient from very wet (pool) to dry (hummock) micro-sites where testate amoebae are often found to respond primarily to the depth to water table (DWT). Much less is known on their responses to finer-scale gradients, and nothing is known of their possible response to phenolic compounds, which play a key role in carbon storage in peatlands. We studied the vertical (0–3, 3–6, and 6–9 cm sampling depths) micro-distribution patterns of testate amoebae in the same microhabitat (Sphagnum fallax lawn) along a narrow ecological gradient between a poor fen with an almost flat and homogeneous Sphagnum carpet (fen) and a “young bog” (bog) with more marked micro-topography and mosaic of poor fen and bog vegetation. We analyzed the relationships between the testate amoeba data and three sets of variables (1) “chemical” (pH, Eh potential, and conductivity), (2) “physical” (water temperature, altitude, i.e., Sphagnum mat micro-topography, and DWT), and (3) phenolic compounds in/from Sphagnum (water-soluble and primarily bound phenolics) as well as the habitat (fen/bog) and the sampling depth. Testate amoeba Shannon H′ diversity, equitability J of communities, and total density peaked in lower parts of Sphagnum, but the patterns differed between the fen and bog micro-sites. Redundancy analyses revealed that testate amoeba communities differed significantly in relation to Eh, conductivity, water temperature, altitude, water-soluble phenolics, habitat, and sampling depth, but not to DWT, pH, or primarily bound phenolics. The sensitivity of testate amoebae to weak environmental gradients makes them particularly good integrators of micro-environmental variations and has implications for their use in paleoecology and environmental monitoring. The correlation between testate amoeba communities and the concentration of water-soluble phenolic suggests direct (e.g., physiological) and/or indirect (e.g., through impact on prey organisms) effects on testate amoebae, which requires further research.
Published: 2011
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44. Effects of short-term ecosystem experimental warming on water-extractable organic matter in an ombrotrophic Sphagnum peatland (Le Forbonnet, France)

Author: Fatima Laggoun-Défarge, Sébastien Gogo, Vincent E. J. Jassey, Jean-Robert Disnar, Alexandre Buttler, Frédéric Delarue, Institut des Sciences de la Terre d'Orléans (ISTO), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Laboratoire des systèmes écologiques (ECOS), Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratoire Chrono-environnement - UFC (UMR 6249) (LCE), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), WSL Lausanne, WSL, INRA - Unité Science du Sol, Institut National de la Recherche Agronomique (INRA), Université de Tours-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), Unité de Science du Sol (Orléans) (URSols), PEATWARM initiative through an ANR (French National Agency for Research) ANR-07-VUL-010, Institut des Sciences de la Terre d'Orléans ( ISTO ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Université d'Orléans ( UO ) -Université de Tours-Centre National de la Recherche Scientifique ( CNRS ), Laboratoire des systèmes écologiques ( ECOS ), Ecole Polytechnique Fédérale de Lausanne ( EPFL ), Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Institut National de la Recherche Agronomique ( INRA ), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), and Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)
Subjects: Peat, 010504 meteorology & atmospheric sciences, Open-Top Chambers, Warmer World, 01 natural sciences, Sphagnum, sphagnum, Soil, Bog, Humic Acids, air warming, chemistry.chemical_classification, Carbon Isotopes, geography.geographical_feature_category, Climate-Change, biology, réchauffement de l'air, Carbon sink, 04 agricultural and veterinary sciences, open-top chamber, [ SDE.MCG ] Environmental Sciences/Global Changes, Environmental chemistry, Poor fen, tourbière d'europe de l'ouest, Ecological Gradients, [SDE.MCG]Environmental Sciences/Global Changes, Ombrotrophic, Chemical-Composition, Soil science, Carbon cycle, Geochemistry and Petrology, [ SDU.ENVI ] Sciences of the Universe [physics]/Continental interfaces, environment, biogeochemical parameter, Organic matter, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, 0105 earth and related environmental sciences, geography, west european mire, organic carbon, sphaigne, 15. Life on land, biology.organism_classification, chemistry, 13. Climate action, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries, Environmental science, peatland, West European Mires
Abstract: In a future warmer world, peatlands may change from a carbon sink function to a carbon source function. This study tracks changes in water-extractable organic matter (WEOM) after 1 year of in situ experimental warming using open top chambers (OTCs). WEOM was studied in the upper peat layers (0-10 cm) through analysis of water-extractable organic carbon (WEOC), stable C isotopic composition (delta C-13), specific UV absorbance at 280 nm and sugar composition of cores taken from an open bog (DRY sites) and a transitional poor fen (WET sites). At the DRY sites, the impact of OTCs was weak with respect to WEOM parameters, whereas at the WET sites, the air warming treatment led to a decrease in peat water content, suggesting that the supply of heat by OTCs was used mainly for evapotranspiration. OTCs at the WET sites also induced a relative enrichment at the surface (0-5 cm depth) of aliphatic and/or aromatic compounds with concomitant decrease in WEOC, as a result of decomposition. On the contrary, WEOC and sugar content increased in the deeper peat layer (7.5-10 cm depth) probably as a result of increased leaching of phenolic compounds by roots, which then inhibits microbial activity. The different response to experimental warming at DRY and WET sites suggests that the spatial variability of moisture is critical for understanding of the impact of global warming on the fate of OM and the carbon cycle in peatlands. (C) 2011 Elsevier Ltd. All rights reserved.
Published: 2011
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45. Experimental warming interacts with soil moisture to discriminate plant responses in an ombrotrophic peatland

Author: Pierre Mariotte, Luca Bragazza, Vincent E. J. Jassey, Sébastien Gogo, Bjorn J. M. Robroek, Edward A. D. Mitchell, Gregory Bernard, Alexandre Buttler, Cédric Pochelon, Frédéric Delarue, Fatima Laggoun-Défarge, Laboratoire des systèmes écologiques (ECOS), Ecole Polytechnique Fédérale de Lausanne (EPFL), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Pôle National Relais Tourbières, Institut de minéralogie et de physique des milieux condensés (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre for Carbon Water and Food Biogeochemistry Group, The University of Sydney, Laboratory of Soil Biology, Université de Neuchâtel (UNINE), Jardin Botanique de Neuchâtel, Biology and Evolution, University of Ferrara, Università degli Studi di Ferrara (UniFE), grant PSPB-013/2010 from Switzerland through the Swiss contribution to the enlarged European UnionSwiss National Science Foundation (no PBELP3 146538)., ANR-10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), ANR-07-VULN-0010,PEATWARM,Impact du réchauffement climatique sur la focntion de puits de carbone de l'ecosysteme tourbières à sphaignes.(2007), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Chrono-environnement - UFC (UMR 6249) (LCE), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Laboratoire de Minéralogie et Cosmochimie du Museum (LMCM), Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), University of Ferrara [Ferrara], ANR-10-LABX-100-01/10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment(2010), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Chrono-environnement (UMR 6249) (LCE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Ferrara = University of Ferrara (UniFE), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des systèmes écologiques ( ECOS ), Ecole Polytechnique Fédérale de Lausanne ( EPFL ), Institut des Sciences de la Terre d'Orléans - UMR7327 ( ISTO ), Bureau de Recherches Géologiques et Minières (BRGM) ( BRGM ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université d'Orléans ( UO ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Laboratoire de Minéralogie et Cosmochimie du Museum (LMCM), UMR 7202 ( LMCM ), Muséum National d'Histoire Naturelle ( MNHN ) -Centre National de la Recherche Scientifique ( CNRS ), The University of Sydney [Sydney], University of Neuchatel, ANR-10-LABX-100-01/10-LABX-0100,VOLTAIRE,Geofluids and Volatil elements – Earth, Atmosphere, Interfaces – Resources and Environment ( 2010 ), and ANR-07-VULN-0010,PEATWARM,Impact du réchauffement climatique sur la focntion de puits de carbone de l'ecosysteme tourbières à sphaignes. ( 2007 )
Subjects: 0106 biological sciences, Vascular plant, Peat, 010504 meteorology & atmospheric sciences, NDVI, Ombrotrophic, Growing season, Point-intercept survey, Plant Science, 010603 evolutionary biology, 01 natural sciences, Sphagnum, point-intercept survey Journal of Vegetation Science, [ SDU.ENVI ] Sciences of the Universe [physics]/Continental interfaces, environment, Climate change, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, 0105 earth and related environmental sciences, Eriophorum vaginatum, Vegetation, Ecology, biology, Drought, Point intercept survey, Temperature, Ambientale, Plant community, 15. Life on land, biology.organism_classification, OTC, 13. Climate action, [SDU]Sciences of the Universe [physics], Environmental science, Climate change, Drought, NDVI, OTC, Point intercept survey, Sphagnum, Temperature, Vegetation, [ SDU ] Sciences of the Universe [physics]
Abstract: International audience; QuestionA better understanding of the response of Sphagnum mosses and associated vascular plants to climate warming is relevant for predicting the carbon balance of peatlands in a warmer world. Open-top chambers (OTCs) have been used to investigate the effect on soil biogeochemical processes in peatlands, but little information is available on the effects of OTCs on microclimate conditions and the associated response of the plant community. We aimed to understand how simulated warming and differences in soil moisture affect plant species cover.LocationA Sphagnum-dominated peatlands in French Jura.MethodsWe used OTCs to measure the effect of a near-ground temperature increase (+1.5 °C on average) on vegetation dynamics over five growing seasons (2008–2012) in a Sphagnum-dominated peatland, in two adjacent microhabitats with different hydrological conditions – wet and dry. Microclimatic conditions and plant species abundance were monitored at peak biomass in years 1, 2, 3 and 5 and monthly during the plant growing season in year 5.ResultsThe response to warming differed between vascular plants and bryophytes, as well as among species within these groups, and also varied in relation to soil moisture. Andromeda polifolia abundance responded positively to warming, while Vaccinium oxycoccus responded negatively, and Eriophorum vaginatum showed a high resistance.ConclusionDepth of rooting of vascular plants appeared to control the response in plant abundance, while moss abundance depended on various other interacting factors, such as shading by the vascular plant community, precipitation and soil moisture.
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46. Functional traits as a new approach for interpreting testate amoeba palaeo-records in peatlands and assessing the causes and consequences of past changes in species composition

Author: Vincent E. J. Jassey, Bertrand Fournier, Enrique Lara, Edward A. D. Mitchell, Laboratoire de biodiversité du sol [Neuchâtel], Université de Neuchâtel (UNINE), Institute of Biology - Laboratory of Soil Biology, and Ecole Polytechnique Fédérale de Lausanne (EPFL)
Subjects: 0106 biological sciences, Assembly rules, Archeology, Peat, community-weighted mean of traits (CWM), [SDE.MCG]Environmental Sciences/Global Changes, Biology, microbial ecology, 010603 evolutionary biology, 01 natural sciences, 03 medical and health sciences, Limiting similarity, Ecosystem, Testate amoebae, ComputingMilieux_MISCELLANEOUS, 030304 developmental biology, Earth-Surface Processes, Abiotic component, 0303 health sciences, Global and Planetary Change, Subfossil, Ecology, Community structure, Paleontology, 15. Life on land, palaeoecology, long-term changes, trait-based approach, transfer function, sense organs, protist
Abstract: Subfossil remains of various groups of organisms preserved in peat and sediment archives are commonly used to infer past environmental changes using transfer functions based on species composition. However, the changes in community structure can also be explored using the functional trait approach. Investigation of functional traits in palaeoecological records can inform about the mechanisms through which abiotic variables such as temperature or moisture impact communities. Moreover, changes in functional traits provide information about changes in ecosystem functioning and can potentially lead to the reconstruction of past processes at the ecosystem scale. Here, we use five key functional traits of arcellinid testate amoebae (TAs), a group of protozoa that are key actors in the microbial foodwebs in peatlands. We apply this approach to the subfossil TA Holocene record of four geographically independent peatlands from Alaska, Switzerland, Poland and Russia. We found that species with larger shells were frequently eliminated from the communities most likely as a result of a switch towards drier conditions. However, when conditions were wetter, species with large shells and species with small shells could coexist because they differed in their trophic niche (i.e. preys). Our results show direct but site-specific links between TA trait data and the depth to water table and pH data inferred from TA species composition. This suggests that past environmental changes influenced both species composition and community function in these ecosystems. Overall, this study demonstrates that species- and trait-based approaches yield complementary information on past environmental changes. For instance, while taxonomic approaches reveal the changes in community composition over time, investigation of traits informs both on the causes and the consequences of these changes on ecosystem functioning.
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