Permafrost of the northern hemisphere is a huge reservoir not only of carbon but also of nitrogen. However, nitrogen cycling in permafrost-affected soils is far less studied than carbon cycling. This is because the traditional permafrost nitrogen cycle paradigm is characterized by a dominance of organic nitrogen cycling (depolymerization of polmyeric to monomeric organic nitrogen with subsequent plant or microbial recycling of monomers) over only very marginal mineral nitrogen cycling (ammonification, nitrification, denitrification). It is being argued that this is caused by stong temperature limitation and low ecosystem inputs and availability of nitrogen. According to the traditional view, also hardly any climate change feedbacks via emissions of the greenhouse gas nitrous oxide are expected, since these require an active mineral nitrogen cycle. However, recent research, e.g., reporting high nitrous oxide emissions, is inconsistent with the traditional paradigm. In addition, climate change, being particulary rapid in the Arctic, could amplify mineral nitrogen ycling in permaforst-affected soils through higher temperatures, altered vegetation, deepened active layers and more fires. Thus, the overall goal of this wirk is to improve the understanding of soil biogeochemical nitrogen turnover processes in permafrost ecosystems.
