They sent
soil samples for DNA testing, looking for matches with particular genes known to be found
in microbes and fungi; they tried to
stimulate microbial growth on a wide variety of substances and then count the cells produced; and they used highly sensitive radiorespiration activity assays, which involve feeding the
soil microorganisms a food source which has been labelled with radioactive carbon, which can then be used to detect if the microorganisms are active.
Given enough oxygen, decomposition of organic matter
in soil is accompanied by the release of heat by
microbes (similar to compost), which, during summer, might
stimulate further permafrost thaw.