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Mitchell, Edward

Nom
Mitchell, Edward
Affiliation principale
Site web
Fonction
Professeur ordinaire
Email
edward.mitchell@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/357
_
0000-0003-0358-506X

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  • Publication
    Accès libre
    Relationship between atmospheric pollution characterized by NO2 concentrations and testate amoebae density and diversity
    (2004)
    Nguyen Viet, Hung
    ;
    Gilbert, Daniel
    ;
    Bernard, Nadine
    ;
    Mitchell, Edward 
    ;
    Badot, Pierre-Marie
    To assess the potential use of testate amoebae as biomonitors of atmospheric pollution we studied the relationship between atmospheric nitrogen dioxide (NO2) pollution and testate amoebae density, diversity, and community structure (Protista: Rhizopoda) in (zone 1) and around (zone 2) the city of Besançon, France. NO2 concentrations were on average significantly lower in the city zone (mean: 34.8±9.5 µg/m3) than in the periphery zone (mean: 14.6±4.7 µg/m3). The density of living amoebae was correlated with that of empty tests (0.001
  • Publication
    Accès libre
    Above- and belowground linkages in Sphagnum peatland: climate warming affects plant-microbial interactions
    Jassey, Vincent E. J.
    ;
    Chiapusio, Geneviève
    ;
    Binet, Philippe
    ;
    Buttler, Alexandre
    ;
    Laggoun-Défarge, Fatima
    ;
    Delarue, Frédéric
    ;
    Bernard, Nadine
    ;
    Mitchell, Edward 
    ;
    Toussaint, Marie-Laure
    ;
    Francez, André-Jean
    ;
    Gilbert, Daniel
    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.