Diversity, resistance and resilience of the bacterial communities at two alpine glacier forefields after a reciprocal soil transplantation

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In this study, we determined the driving key factor determining variability in bacterial community structures in soils at two unvegetated alpine glacier forefields with different bedrock geology (calcareous and siliceous). We further assessed the resistance and resilience capacities of the bacterial communities through reciprocal soil transplantations. Sterilized and unsterilized soils were incubated locally ('home') or transplanted ('away') for 15 months (July 2011-October 2012) and sampled regularly during the snow-free seasons. Changes in bacterial community structures were determined through fingerprinting of the 16S rRNA gene and correlated with several environmental factors. This study demonstrates that bacterial community structures at our field sites were shaped by distinct mineralogical soil properties. Soil moisture and pH appeared to not be the major driving key factors. Calcareous soil was more selective to bacteria, thus diversity was higher in siliceous soils as a positive effect of its more diverse mineralogical composition. Bacterial community in the calcareous soil exhibited stronger resistance to transplantation than the community in the siliceous soil. In fact, siliceous soil was more easily invaded by extrinsic taxa. Bacterial communities of both soil types were equally resilient at home, although different resilience patterns were observed between calcareous and siliceous soils incubated away.