The project aims to describe the effects of increased frequency of freeze-thaw cycles on the soil fauna in an arctic environment. Little is known about the effects of global warming on soil animals in habitats of limited nutrient supply and with high climatic stress. Manipulations of the soil temperature will be conducted to increase the frequency of freeze-thaw events. Springtail and mite species diversity and abundance will be investigated, together with screenings of the nutrient availability in the soil after such events. Mesocosm studies will be conducted for a closer study of the effects of temperature changes on decomposition and mineralization. Species of springtails and mites will be returned to the laboratory to investigate cold and drought hardiness. A project including soil warming has been conducted in Abisko for over a decade, and it is our intent to include investigations of soil fauna (springtails and mites), and the interactions between these and the microbial fauna. It is interesting to see whether 10 years of soil warming have changed the springtail and mite species diversity and abundance, and whether this has affected the natural nutrient cycles.