Given that it is generally accepted that the climate is changing, it is essential to investigate the effects that changes in climate parameters (temperature, precipitation) will have on the soil C cycle (through changes in inputs and outputs) and on the activity of soil microorganisms. Soils provide essential ecosystem services such as primary production, regulation of biogeochemical cycles and their consequences on climate, water filtration, resistance to diseases and pests, and regulation of above-ground biodiversity. Concomitantly, soils are exposed to many anthropogenic threats. Scientific and technological knowledge on soil biodiversity and functioning in relation to ecosystem services is required for reaching such a goal. Soils host a huge diversity of microbes (archaea, bacteria, fungi) and fauna (protozoa, microarthropods, nematodes, oligochaeta) for which our SS knowledge of function and diversity remains very limited. This is related to the small size of the soilborne organisms, their diversity, the difficulty of accessing them, and to the great heterogeneity of their habitats at different scale levels. However, recent progresses in the molecular characterization of the biodiversity raises stimulating prospects to explore its complexity and better understand its functioning. Soil microorganisms, the central drivers of terrestrial Antarctic ecosystems, are being confronted with increasing temperatures as parts of the continent experience considerable warming. Here we determined short-term temperature dependencies of Antarctic soil bacterial community growth rates, using the leucine incorporation technique, in order to predict future changes in temperature sensitivity of resident soil bacterial communities. In this study soil samples were collected along a climate gradient consisting of locations on the central Iran in Semnan city. The result demonstrated that the bacterial communities were adapted to the mean annual temperature of their environment, as shown by a significant correlation between the mean annual soil temperature and the minimum temperature for bacterial growth (Tmin). Every 1 1C rise in soil temperature was estimated to increase Tmin by 0.24–0.38 1C. The optimum temperature for bacterial growth varied less and did not have as clear a relationship with soil temperature. Temperature sensitivity, indicated by Q10 values, increased with mean annual soil temperature, suggesting that bacterial communities from colder regions were less temperature sensitive than those from the warmer regions.
