Vignette d'image

Koenig, Isabelle

Nom
Koenig, Isabelle
Affiliation principale
Site web
Fonction
PhD Student
Email
isabelle.koenig@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/756

Résultat de la recherche

Filtres

2
2
2
Réinitialiser les filtres

Paramètres

Voici les éléments 1 - 2 sur 2
  • Publication
    Accès libre
    Soil chemistry changes beneath decomposing cadavers over a one-year period
    (2018-3-6)
    Szelecz, Ildiko 
    ;
    Koenig, Isabelle 
    ;
    Seppey, Christophe V.W.
    ;
    Le Bayon, Renée-Claire 
    ;
    Mitchell, Edward 
    Decomposing vertebrate cadavers release large, localized inputs of nutrients. These temporally limited resource patches affect nutrient cycling and soil organisms. The impact of decomposing cadavers on soil chemistry is relevant to soil biology, as a natural disturbance, and forensic science, to estimate the postmortem interval. However, cadaver impacts on soils are rarely studied, making it difficult to identify common patterns. We investigated the effects of decomposing pig cadavers (Sus scrofa domesticus) on soil chemistry (pH, ammonium, nitrate, nitrogen, phosphorous, potassium and carbon) over a one-year period in a sprucedominant forest. Four treatments were applied, each with five replicates: two treatments including pig cadavers (placed on the ground and hung one metre above ground) and two controls (bare soil and bags filled with soil placed on the ground i.e. “fake pig” treatment). In the first two months (15–59 days after the start of the experiment), cadavers caused significant increases of ammonium, nitrogen, phosphorous and potassium (p < 0.05) whereas nitrate significantly increased towards the end of the study (263–367 days; p < 0.05). Soil pH increased significantly at first and then decreased significantly at the end of the experiment. After one year, some markers returned to basal levels (i.e. not significantly different from control plots), whereas others were still significantly different. Based on these response patterns and in comparison with previous studies, we define three categories of chemical markers that may have the potential to date the time since death: early peak markers (EPM), late peak markers (LPM) and late decrease markers (LDM). The marker categories will enhance our understanding of soil processes and can be highly useful when changes in soil chemistry are related to changes in the composition of soil organism communities. For actual casework further studies and more data are necessary to refine the marker categories along a more precise timeline and to develop a method that can be used in court.
  • Publication
    Accès libre
    Comparative ecology of vascular plant, bryophyte and testate amoeba communities in four Sphagnum peatlands along an altitudinal gradient in Switzerland
    (2015-3-4)
    Koenig, Isabelle 
    ;
    Feldmeyer-Christe, Elizabeth
    ;
    Mitchell, Edward 
    Monitoring tools are needed to assess changes in peatland biotic communities and ecosystem functions inresponse to on-going climate and other environmental changes. Although the responses of soil organismsand plants to ecological gradients and perturbations do not always correlate, peatland monitoring ismainly based on vegetation surveys. Testate amoebae, a group of protists, are important contributorsto carbon and nitrogen cycling in organic soils and are useful bioindicators in peatland ecology andpaleoecology. There is however little comparative data on the value of testate amoebae, vascular plantsand bryophytes as bioindicators of micro-environmental gradients in peatlands.We compared the relationships of testate amoebae, bryophytes, and vascular plants with soil tempera-ture, water table depth, micro-habitats and the carbon and nitrogen content of Sphagnum mosses in fourpeatlands along a 1300 m altitudinal gradient in Switzerland. We used the full diversity of vascular plantsand bryophyte but only a selection of ten easily identifiable testate amoeba morpho-taxa (i.e. species orspecies-complexes).Indirect and direct gradient ordinations, multiple factor analysis (MFA) and transfer function modelsfor inferring water table depth showed that a selection of ten testate amoeba taxa are more powerful (%variance explained in RDA) and accurate (discrimination among habitats) indicators of local conditions(micro-habitat type, water table depth and Sphagnum C/N ratio) than the vegetation (vascular plants andbryophytes either individually or combined and considering the full diversity).Our study showed that a limited list of ten easily identifiable testate amoeba taxa have higher bioindi-cation value than the full bryophytes and vascular plants. Furthermore, testate amoebae can be analyzedon samples collected at any season (accessibility allowing and if precise sampling sites are well marked)– a clear advantage for biomonitoring and can be used to infer past changes from the peat record at thesame taxonomic resolution. This simple approach could therefore be very useful for biomonitoring ofpeatlands.