Effects of snow cover-induced microclimate warming on soil physicochemical and biotic properties

The continuing warming of the climate system is reducing snow cover depth and duration worldwide. Changes in snow cover can significantly affect the soil microclimate and the functioning of many terrestrial ecosystems across latitudinal and elevational gradients. Yet, a quantitative assessment of the effects of snow cover change on soil physicochemical and biotic properties at large or regional scales is lacking. Here, we synthesized data of 3286 observations from 99 publications of snow manipulation studies to evaluate the effects of snow removal, addition, and compaction on soil physicochemical and biotic properties in winter and in the following growing season across (sub)arctic, boreal, temperate, and alpine regions. We found that (1) snow removal significantly reduced soil temperature by 2.2 and 0.9 °C in winter and in the growing season, respectively, while snow addition increased soil temperature in winter by 2.7 °C but only by 0.4 °C in the following growing season whereas snow compaction had no effect; (2) snow removal had limited effects on soil properties in winter but significantly affected soil moisture, pH, and carbon (C) and nitrogen (N) dynamics in the growing season; (3) snow addition had significant effects on soil properties both in winter (e.g., increases in soil moisture, soil C and N dynamics, phosphorus availability, and microbial biomass C and N) and in the growing season (e.g., increases in mineral N, microbial biomass C and N, and enzyme activities); and (4) the effects of snow manipulation on soil properties were regulated by moderator variables such as ecosystem type, snow depth, latitude, elevation, climate, and experimental duration. Overall, our results highlight the importance of snow cover-induced warmer microclimate in regulating soil physicochemical and biotic properties at regional scales. These findings are important for predicting and managing changes in snow-covered ecosystems under future climate change scenarios.