The activity and functions of subarctic soil microbial communities vary across vegetation types

Abstract Global warming changes the activity of soil microbial communities in high latitudes, which might result in higher greenhouse gas emissions. However, these microbial processes involved in GHG production and consumption are not thoroughly understood. We analyzed 116 soil metatranscriptomes from 73 tundra sites and investigated how bacterial and archaeal communities and their functions vary horizontally (i.e. vegetation type) and vertically (i.e. topsoil organic and mineral layers) during the summer season, in soil types that differed in pH, moisture, soil organic matter (SOM), and carbon and nitrogen content. Active microbial communities were significantly different in the organic and mineral soil layers. Additionally, the communities differed significantly between the different vegetation types both in the organic and mineral layers. Various plant polymer degraders were particularly active in shrub-dominated ecosystems with high SOM and low pH, less known mixotrophic groups (such as Chloroflexi) were active lower SOM and higher pH. Additionally, we detected transcripts of alphaproteobacterial methanothrophs, which potentially moderate methane release from tundra soils in deeper soil layer. Our results provide new insights into the diversity and activity of microbial communities of high latitudes under climate change.