Three-year incubation of tundra soil collected from the Carbon in Permafrost Experimental Heating Research (CiPEHR) experimental site in May 2010. Alaskan tundra soil long-term incubation experiment

A warming experiment was carried out at the Carbon in Permafrost Experimental Heating Research (CiPEHR) site, which was established in 2008. Soils were warmed during the winters months by increasing snow cover behind the snow fences, which were perpendicular to the dominant south-easterly winter winds. Warming plots were on the leeward side of the snow fences while the control plots were on the windward side. The snow fences trapped and accumulated an insulating snow layer on the warming plots. As a result, the warmed soil was at an average temperature of 2.3oC higher than the control soil during winters. Soil samples that had been subjected to the warming treatment for 1.5 years were collected in May 2010. Soil was collected from a depth of 15–25 cm in order to avoid litter and course root that made up the majority of the tundra soil from 0–15 cm. To deplete the labile C, soil samples were incubated by incubation in jars for 975 days. DNA extraction and metagenomic sequencing of end-point incubations was performed to assess soil microbial community composition at the end of the experiment.