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Derungs, Nicolas

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Derungs, Nicolas
Affiliation principale
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Ancien.ne collaborateur.trice
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https://libra.unine.ch/handle/123456789/368

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  • Publication
    Accès libre
    Chemical and Biological Gradients along the Damma Glacier Soil Chronosequence, Switzerland
    (2011)
    Bernasconi, Stefano M.
    ;
    Bauder, Andreas
    ;
    Bourdon, Bernard
    ;
    Brunner, Ivano
    ;
    Bünemann, Else
    ;
    Chris, Iso
    ;
    Derungs, Nicolas 
    ;
    Edwards, Peter
    ;
    Farinotti, Daniel
    ;
    Frey, Beat
    ;
    Frossard, Emmanuel
    ;
    Furrer, Gerhard
    ;
    Gierga, Merle
    ;
    Göransson, Hans
    ;
    Gülland, Kathy
    ;
    Hagedorn, Frank
    ;
    Hajdas, Irka
    ;
    Hindshawc, Ruth
    ;
    Ivy-Ochs, Susan
    ;
    Jansa, Jan
    ;
    Jonas, Tobias
    ;
    Kiczkac, Mirjam
    ;
    Kretzschmar, Ruben
    ;
    Lemarchand, Emmanuel
    ;
    Luster, Jörg
    ;
    Magnusson, Jan
    ;
    Mitchell, Edward 
    ;
    Venterink, Harry Olde
    ;
    Plötze, Michael
    ;
    Reynolds, Ben
    ;
    Smittenberg, Rienk H.
    ;
    Stähli, Manfred
    ;
    Tamburini, Federica
    ;
    Tipper, Edward T.
    ;
    Wacker, Lukas
    ;
    Welc, Monika
    ;
    Wiederhold, Jan G.
    ;
    Zeyer, Josef
    ;
    Zimmermann, Stefan
    ;
    Zumsteg, Anita
    Soils are the product of a complex suite of chemical, biological, and physical processes. In spite of the importance of soils for society and for sustaining life on earth, our knowledge of soil formation rates and of the influence of biological activity on mineral weathering and geochemical cycles is still limited. In this paper we provide a description of the Damma Glacier Critical Zone Observatory and present a first synthesis of our multidisciplinary studies of the 150-yr soil chronosequence. The aim of our research was to improve our understanding of ecosystem development on a barren substrate and the early evolution of soils and to evaluate the influence of biological activity on weathering rates. Soil pH, cation exchange capacity, biomass, bacterial and fungal populations, and soil organic matter show clear gradients related to soil age, in spite of the extreme heterogeneity of the ecosystem. The bulk mineralogy and inorganic geochemistry of the soils, in contrast, are independent of soil age and only in older soils (>100 yr) is incipient weathering observed, mainly as a decreasing content in albite and biotite by coincidental formation of secondary chlorites in the clay fraction. Further, we document the rapid evolution of microbial and plant communities along the chronosequence.
  • Publication
    Accès libre
    Testate Amoebae Like It Hot: Species Richness Decreases Along a Subalpine-Alpine Altitudinal Gradient in Both Natural Calluna vulgaris Litter and Transplanted Minuartia sedoides Cushions
    Heger, Thierry J
    ;
    Derungs, Nicolas 
    ;
    Theurillat, Jean-Paul
    ;
    Mitchell, Edward 
    Most groups of higher organisms show a decrease in species richness toward high altitude, but the existence of such a pattern is debated for micro-eukaryotes. Existing data are scarce and mostly confounded with the diversity of habitats that also decreases with elevation. In order to disentangle these two factors, one approach is to consider only similar types of habitats occurring across an elevational gradient. We assessed the diversity and community structure of testate amoebae in two specific habitats: (1) natural Calluna vulgaris litter and (2) Minuartia sedoides cushions 7 years after their transplantation along a vertical transect from 1770 to 2430 m in the subalpine and alpine zones of the Swiss Alps. Analyses of co-variance and variance showed that testate amoeba species richness, equitability, and diversity declined with elevation and were significantly correlated to habitat type. In a redundancy analysis, the variation in the relative abundance of the testate amoeba taxa in Calluna vulgaris litter was equally explained by elevation and litter pH. This is the first study documenting a monotonic decrease of protist diversity in similar habitats across an elevational gradient.
  • Publication
    Accès libre
    Thécamoebiens muscicoles d'un mur d’enceinte du château de Neuchâtel – les protistes constituent-ils une partie négligeable de la biodiversité ou plutôt une « majorité silencieuse » ?
    Mitchell, Edward 
    ;
    Arnet, Thierry
    ;
    Chatelain, Auriel
    ;
    Derungs, Nicolas 
    ;
    Lara, Enrique 
    L’analyse de quelques échantillons de mousses poussant sur le mur d'enceinte du château de Neuchâtel a révélé la présence de 23 taxons de thécamoebiens : dont 10 Euglyphides et 13 Arcellinides sur un total de 117 espèces recensées au total, tous groupes taxonomiques confondus. Ce total de 23 taxons est sans doute une sous-estimation compte-tenu des découvertes récentes d’une diversité inconnue d’espèces et taxons de rangs supérieurs au sein des différents groupes de protistes, y compris chez les thécamoebiens. Ces résultats illustrent le potentiel de découverte d’une diversité méconnue dans le monde microbien, même dans des régions où la diversité des organismes vivants a été bien étudiée depuis des siècles., The analysis of a few moss samples collected on the walls of the castle of Neuchâtel has revealed the presence of 23 taxa of testate amoebae, among which 10 Euglyphids and 13 Arcellinids, out of an overall total of 117 observed taxa, for all taxonomic groups. As hitherto unknown species and higher taxa are continuously being discovered within the various groups of protists including testate amoebae, this total of 23 taxa is most likely an underestimation. These results illustrate the potential for discovery of a poorly known diversity within the microbial world, including in regions where the diversity of living organisms has been well studied for centuries.