Permafrost degradation and organic matter decomposition in the terrestrial Arctic are strongly
depending on soil temperature throughout the year. These temperatures are affected in numerous
ways by activity of large herbivorous animals. We identified snow compaction and animal-induced
vegetation changes as key elements. Therefore, we analysed soil parameters along transects
following grazing intensity in both a permafrost environment (northeastern Siberia) and seasonally
frozen ground (norther Finland). Parameters included TOC, C/N ratio, d13C, bulk density and
radiocarbon age. While we observed a strong increase in soil carbon storage with high grazing
intensity under permafrost conditions, this effect does not show in seasonally frozen ground.
However, an obvious animal-induced change in both areas was a shift in vegetation composition and
structure, following the grazing gradient. We conclude that material and water fluxes in seasonally
frozen ground outweigh the animals’ effects, contrary to permafrost environments, but state that
on permafrost, animals could help maintaining low soil temperatures and hence reduce organic
material decomposition
