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Koenig, Isabelle
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Koenig, Isabelle
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- PublicationAccès libreResponse of Sphagnum Testate Amoebae to Drainage, Subsequent Re-wetting and Associated Changes in the Moss Carpet: Results from a Three Year Mesocosm Experiment
; ; Sphagnum peatlands represent a globally significant pool and sink of carbon but these functions are threatened by ongoing climate change. Testate amoebae are useful bioindicators of hydrological changes, but little experimental work has been done on the impact of water table changes on communities.
Using a mesocosm experimental setting that was previously used to assess the impact of drought disturbance on communities and ecosystem processes with three contrasted water table positions: wet (–4 cm), intermediate (–15 cm) and dry (–25 cm), we studied the capacity of testate amoeba communities to recover when the water table was kept at –10 cm for all plots. The overall experiment lasted three years. We assessed the taxonomic and functional trait responses of testate amoeba communities. The selected traits were hypothesised to be correlated to moisture content (response traits: shell size, aperture position) or trophic role (effect traits: mixotrophy, aperture size controlling prey range).
During the disturbance phase, the mixotrophic species Hyalosphenia papilio dominated the wet and intermediate plots, while the community shifted to a dominance of “dry indicators” (Corythion dubium, Nebela tincta, Cryptodifflugia oviformis) and corresponding traits (loss of mixotrophy, and dominance of smaller taxa with ventral or ventral-central aperture) in dry plots. During the recovery phase we observed two contrasted trends in the previously wet and intermediate plots: communities remained similar where the Sphagnum carpet remained intact but species and traits indicators of drier conditions increased in plots where it had degraded. In the former dry plots, indicators and traits of wet conditions increased by the end of the experiment.
This is one of the first experiment simulating a disturbance and subsequent recovery in ex-situ mesocosms of Sphagnum peatland focusing on the response of testate amoebae community structure as well as functional traits to water table manipulation. The results generally confirmed that testate amoebae respond within a few months to hydrological changes and thus represent useful bioindicators for assessing current and past hydrological changes in Sphagnum peatlands. - PublicationAccès libreCreation of a raised bog in the Botanical garden of Neuchâtel: a tool for research, collections and public information
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This object corresponds to the three missions of the garden : 1) to inform the public as well as students about these unusual, fragile and threatened ecosystems, 2) to present characteristic peatland plants from the Jura Mountains (Sphagnum, Drosera, Eriophorum, Betula nana, etc.), and 3) to conduct research projects.
During the winter 2014-15, the snow remained longer on the peatbog that on the adjacent path and meadow, thus providing evidence for a microclimatic effect of the bog. The excessively dry and hot summer 2015 allowed testing the resistance of the newly established bog vegetation. Most plants resisted well, including graminoids Eriophorum vaginatum, Trichophorum cespitosum or Carex sp., ericaceous (Vaccinium oxycoccos, myrtillus and vitis-idea) and mosses (especially Sphagnum). This living laboratory provides a unique opportunity to inform the public about the characteristics and functions of these ecosystems and the challenges of conserving and restoring them in a warmer world.