Global warming; Glacier retreat; Soil formation; Microbial communities; Sequencing; Genetic profiling; Carbon; 13 C stable isotope probing
Rime Thomas, Hartmann Martin, Stierli Beat, Anesio Alexandre, Frey Beat (2016), Assimilation of microbial and plant carbon by active prokaryotic and fungal populations in glacial forefields, in Soil Biology and Biochemistry
, 98, 30-41.
Rime Thomas, Hartmann Martin, Brunner Ivano, Widmer Franco, Zeyer Josef, Frey Beat (2015), Vertical distribution of the soil microbiota along a successional gradient in a glacier forefield, in Molecular Ecology
, 24, 1091-1108.
Rime Thomas, Frey Beat (2015), Wie das Leben an Boden gewinnt. - Comment la vie gagne-t-elle du terrain?, in Geopanorama
, 3, 5-11.
Zumsteg Anita, Schmutz Stefan, Frey Beat (2013), Identification of biomass utilizing bacteria in a carbon-depleted glacier forefield soil by the use of 13C DNA stable isotope probing, in Environmental Microbiology Reports
, 5, 424-437.
Frey Beat, Bühler Lukas, Schmutz Stefan, Zumsteg Anita, Furrer Gerhard (2013), Molecular characterization of phototrophic microorganisms in the forefield of a receding glacier in the Swiss Alps, in Environmental Research Letters
, 8, 015033.
Frey Beat, Rime Thomas, Phillips Marcia, Stierli Beat, Haydas Irka, Widmer Franco, Hartmann Martin, Microbial diversity in European alpine permafrost and active layers, in FEMS Microbiol. Ecol
Rime Thomas, Hartmann Martin, Frey Beat, Potential sources of microbial colonizers in an initial soil ecosystem after retreat of an alpine glacier, in The ISME Journal
BackgroundThe majority of Swiss glaciers are currently receding as a consequence of global warming. Before the initiation of primary succession in the botanical sense on newly deglaciated land, there is a primary microbial succession. Organic C derived from both local (autochthonous) and distant (allochthonous) sources, as a component of the wind-borne debris, is crucial to fuel primary mineral colonizers. Bacterial growth rates in the Damma glacier forefield, however, seem to be universally C limited (Göransson et al. 2011). Photoautotrophs may represent an important source of new C, which may partly sustain heterotrophic communities. Whether heterotrophic microbes benefit from modern or allochthonous C sources has not yet been elucidated in the Damma glacier forefield. The relative magnitudes of the different C sources still needs to be investigated. Quantifying C pools and fluxes in newly deglaciated land and glacier surfaces at present is therefore of great significance for regional, and potentially global, C budgets and predicting future change (Stibal et al. 2008).Working hypotheses:H1: Active photoautotrophic microorganisms are abundant on newly deglaciated landH2: Microbial primary production is significant compared to the allochthonous organic matterH3: Heterotrophic microbes benefit from modern (photoautotrophic fixed CO2) carbonSpecific aims:The goals of the proposed project are threefold: (1) to characterize the structure and diversity of photoautotrophic microorganisms in newly exposed rock substrates; (2) to estimate the relative magnitudes of autochthonous and allochthonous carbon sources, and (3) to examine whether heterotrophic mineral colonizers acquire C by utilizing photoautotrophic-derived or allochthonous C sources.Experimental design and methods:The study site of the proposed project will be the forefield of the Damma glacier (Frey et al. 2010a). A sampling grid consisting of 48 sampling points will be established. The grid lays between two contrasting border moraines representing the extreme points within newly deglaciated land starting at the top of glacier and ending 40 meters away from the glacier tongue where the first plants had been established. First, genetic profiling analyses of DNA directly extracted from barren ground together with phylogenetic identification using SSU rRNA gene sequences and ITS libraries will be applied to characterize the structure and composition of photoautotrophic microorganisms. We will test whether abundance and diversity differ between the extreme points (microclimatic effects) or with distance from the glacier. Second, we will estimate the magnitudes of autochthonous primary production and allochthonous organic carbon input in newly deglaciated land. The comparison of microbial C production and/ or community respiration with values of in situ rates of primary production will allow to elucidate whether that there is the potential for newly deglaciated land to be net autotrophic or net heterotrophic. Third, in order to evaluate the C utilization of heterotrophic microbes, a 13C-labelling field experiment with different carbon sources will be performed. Mineral colonizers will be exposed to 13C-labelled OM and the uptake and incorporation of the label into microbes will be determined. In order to follow the fate of 13C-labelled OM, 13C-assimilating heterotrophic microbes will be identified by 13C-PLFA GC-MS. Expected value of the proposed projectThis project brings completely novel insights into microbial primary production and community respiration in newly deglaciated land. We will assess for the first time the role of primary mineral colonizers within the carbon flow and outline the general importance of photoautotrophs. Newly deglaciated land has the potential to play a significant role in regional, and possibly global, carbon budgets by means of primary production and respiration. Such information has, however, never been gained before in temperate Alpine glacier forefields, although the combined action of autotrophic producers and heterotrophic consumers are crucial for the build-up of organic matter in pioneering ecosystem.