Siberian studies performed over the last decades have detected a general increase in temperature and an increase in winter precipitation leading to a thicker snow pack. Climate models predict an amplification of these trends and indicate that the huge territory of the western Siberian plains will become suitable for agriculture. However, the projections do not consider soil fertility - a key issue for agricultural sustainability. The intention of our study is to test whether the predicted increase in snow precipitation will change the soil water fluxes, soil organic matter (SOM) decomposition, and the rate of nutrient release caused by reduced soil freezing. Investigations were performed in forests and grasslands close to Barnaul, in the steppe zone, and close to Tomsk, in the taiga zone. The sites were characterized for their climate, snow cover, pedoclimate and root patterns. A pair plot experiment was conducted to investigate the effect of snow thickness on soil temperature, moisture, and on the release of nutrients during SOM decomposition. Snow cover was artificially increased in the treatment plot and was undisturbed in the control plot. The impact of snow thickness on soil moisture and temperature was continuously monitored over one year. The release of nitrogen (N) from decaying litter was investigated using 15N isotope tracing. Enzyme activities relevant to the release of N and phosphorus (P) from SOM were measured. At all sites, N and P stocks were large, with organic P representing a high proportion of total P in the topsoil. The increase of snow cover raises the soil T°C over winter and enhances the soil water content after snowmelt. It impacts enzyme activities and the release of N from decomposing litter. These results showed that climate change in Western Siberia may affect soil fertility and the potential of soils to sustain agriculture after conversion of forest and grassland into cropland.