Reduced snow cover accelerates seasonal shifts in soil microbial functioning in alpine grassland. Snow manipulation in alpine grassland

Soil microbial communities drive major biogeochemical cycles. Understanding how soil microbialthese communities respond to climate change, and how this influences biogeochemical cycles represents a major challenge. This is especially important in alpine regions where climate change is taking place at double the rate of the northern hemisphere average and large reductions in snow cover are expected. Here we show for an alpine grassland that spring snowmelt triggers an abrupt shift in the composition and functioning potential of soil microbial communities that is closely linked to a transition in biogeochemical cycling. Further, by experimentally manipulating snow cover, we show that this abrupt seasonal transition in soil microbial communities is advanced by earlier snowmelt. Given distinct differences in the functioning potential of winter and summer soil microbial communities, our results suggest that earlier snowmelt with climate change canould have far reaching consequences for biogeochemical cycling and plant growth in these vulnerable, globally widespread alpine ecosystems.