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Gobat, Jean-Michel
Nom
Gobat, Jean-Michel
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jean-michel.gobat@unine.ch
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Voici les éléments 1 - 10 sur 19
- PublicationMétadonnées seulementSeasonal dynamics of plant species at fine scale in wooded pastures(Budapest: Akademiai Kiado, 2005)
;Kohler, Florian; ;Progin, Marie-Aude; ;Buttler, Alexandre ;Feldmeyer-Christe, E ;Ghosh, S ;Podani, J ;Wildi, OZimmermann, N E - PublicationMétadonnées seulementSoil microbial community changes in wooded mountain pastures due to simulated effects of cattle grazing(2005)
;Kohler, Florian ;Hamelin, Jérôme; ; Buttler, AlexandreThe effect of cattle activity on pastures can be subdivided into three categories of disturbances: herbage removal, dunging and trampling. The objective of this study was to assess separately or in combination the effect of these factors on the potential activities of soil microbial communities and to compare these effects with those of soil properties and plant composition or biomass. Controlled treatments simulating the three factors were applied in a fenced area including a light gradient (sunny and shady situation): (i) repeated mowing; (ii) trampling; (iii) fertilizing with a liquid mixture of dung and urine. In the third year of the experiment, community level physiological profiles (CLPP) (Biolog Ecoplates (TM)) were measured for each plots. Furthermore soil chemical properties (pH, total organic carbon, total nitrogen and total phosphorus), plant species composition and plant biomass were also assessed. Despite differences in plant communities and soil properties, the metabolic potential of the microbial community in the sunny and in the shady situations were similar. Effects of treatments on microbial communities were more pronounced in the sunny than in the shady situation. In both cases, repeated mowing was the first factor retained for explaining functional variations. In contrast, fertilizing was not a significant factor. The vegetation explained a high proportion of variation of the microbial community descriptors in the sunny situation, while no significant variation appeared under shady condition. The three components of cattle activities influenced differently the soil microbial communities and this depended on the light conditions within the wooded pasture. Cattle activities may also change spatially at a fine scale and short-term and induce changes in the microbial community structure. Thus, the shifting mosaic that has been described for the vegetation of pastures may also apply for below-ground microbial communities. - PublicationMétadonnées seulementSpatio-temporal pattern of bog pine (Pinus uncinata var. rotundata) at the interface with the Norway spruce (Picea abies) belt on the edge of a raised bog in the Jura Mountains, Switzerland(2004)
;Freléchoux, François ;Buttler, Alexandre ;Schweingruber, FritzIn a bog site in way of paludification, a pine stand is declining, which presently is an infrequent phenomenon on the Swiss Jura scale. A transect was positioned in the bog, from the external and driest part (pine-spruce stand) towards the central and wettest part (pine stand). Water table, tree structure, tree age structure and pine radial growth were analysed with spatial and temporal references. The ground water level is very shallow and the hydrologic gradient is obvious during dry periods. Tree structure (height and diameter) is strongly linked to the hydrologic gradient. Two cohorts have invaded the bog with a 70-year-time period between them. The first one concerned the whole transect; it started around 1840 and could be related to a clear cutting on the fringe of the bog. After a quick initial radial growth, the pines reduced their radial growth abruptly (1870-1885), more quickly and strongly in the centre of the bog, where an important mortality was observed over the last 10 years. Bog pine can thus survive over decades with a very reduced growth and in very bogs probably constituted the bog pines' survival niche during paludification in the Jura bogs. - PublicationMétadonnées seulementSeasonal dynamics of plant species at fine scale in wooded pastures(2004)
;Kohler, Florian; ;Progin, Marie-Aude; Buttler, Alexandre - PublicationMétadonnées seulementSuccession from bog pine (Pinus uncinata var. rotundata) to Norway spruce (Picea abies) stands in relation to anthropic factors in Les Saignolis bog, Jura Mountains, Switzerland(2003)
;Freléchoux, François ;Buttler, Alexandre; ; Schweingruber, FritzIn Jura bogs, on deep and nutrient-poor peat, the ecotone between bog pine forest and Norway spruce forest is sharp and, in a few disturbed situations, no succession pine forest-spruce forest occurs. The bog Les Saignolis lies at the top of an anticline, on thin and oligotrophic peat. Several documents attest some anthropic disturbances (clear cut and drainage). Beside these historical data and with the aim of reconstructing vegetation dynamics and tree growth, we realised synusial phytosociological releves and, in a mixed pine-spruce stand, we studied tree radial growth. Following the clear cut, the bog pine, the pubescent birch, and the Norway spruce settled simultaneously. The birch disappeared rapidly. The present cohort of pine settled and grew rapidly, and then declined because of the competition by spruce. Spruce settled progressively and increased its growth regularly except when pine settled and grew. Interspecific competition between pines and spruces and intraspecific competition between dominant and sub-dominant spruces were put into evidence by radial growth analysis. - PublicationMétadonnées seulementContrasted effects of increased N and CO2 supply on two keystone species in peatland restoration and implications for global change(2002-5-2)
; ;Buttler, Alexandre ;Grosvernier, Philippe ;Rydin, Hakan ;Siegenthaler, Andy1 Significant areas of temperate bogs have been damaged by peat harvesting but may regenerate. These secondary mires, if well managed, may act as strong C sinks, regulate hydrology and buffer regional climate. 2 The potential effects of bog regeneration will, however, depend on the successful establishment of the principal peat formers - Sphagnum mosses. The influence of hydrology and microclimate on Sphagnum re-growth is well studied but effects of elevated CO2 and N deposition are not known. 3 We carried out two in-situ experiments in a cutover bog during three growing seasons in which we raised either CO2 (to 560 p.p.m.) or N (by adding NH4NO3, 3 g m(-2) year(-1)). The two treatments had contrasting effects on competition between the initial coloniser Polytrichum strictum (favoured by high N) and the later coloniser Sphagnum fallax (favoured by high CO2). 4 Such changes may have important consequences for bog regeneration and hence for carbon sequestration in cutover bogs, with potential feedback on regional hydrological and climatic processes. - PublicationMétadonnées seulementRuptures multiples dans les tourbières du Jura: changements climatiques et hydrologiques, successions végétales et impacts humains(: DIALOGUES D'HISTOIRE ANCIENNE, 2002)
;Buttler, Alexandre; ;Freléchoux, François ;Van der Knaap, Willem ;Van Leeuwen, Jacqueline ;Warner, Barry; ;Schweingruber, FritzAmman, Brigitte - PublicationMétadonnées seulementCan testate amoebae (Protozoa) and other micro-organisms help to overcome biogeographic bias in large scale global change research?(: Kluwer Academic Publishers, 2001)
; ;Gilbert, Daniel ;Butler, Alexandre ;Grosvernier, Philippe ;Albinsson, Christer ;Rydin, Hakan ;Buttler, Alexandre ;Heijmans, Monique ;Hoosbeek, Marcel ;Greenup, Alisson ;Foot, Jonathan ;Saarinen, Timo ;Vasander, Harri - PublicationMétadonnées seulementEffects of elevated CO2 and nitrogen deposition on natural regeneration processes of cut-over ombrotrophic peat bogs in the Swiss Jura mountains(: Kluwer Academic Publishers, 2001)
;Grosvernier, Philippe; ;Buttler, Alexandre - PublicationMétadonnées seulementVégétation et flore(Lausanne, Paris: Delachaux, Niestlé, 2001)
;Buttler, Alexandre; ; Blant, Michel