The activity and functions of soil microbial communities in the Finnish sub-Arctic 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.

In-depth characterization of denitrifier communities across different soil ecosystems in the tundra

“…1a–c) . In previous studies, we have established in the area a systematic fine-scale sampling of microclimate, soil conditions, and vegetation in topographically distinct environments [40, 75, 76]. Local variation in topography and soil properties creates a mosaic of habitats characterized by contrasting ecological conditions.…”

“…Local variation in topography and soil properties creates a mosaic of habitats characterized by contrasting ecological conditions. This makes the study setting ideal to investigate species-environment relationships and ecosystem functioning in the tundra [40, 77, 78]. Soil ecosystems differed in vegetation cover and physicochemical composition, with fens being characterized by higher pH, moisture, and N content (one-way ANOVA, R 2 = 0.10–0.66, p < 0.001) and, together with the meadows, lower C:N ratio (one-way ANOVA, R 2 = 0.55, p < 0.001) (Fig.…”

“…Total DNA and RNA were co-extracted as previously described [40]. Briefly, extraction was performed on 0.5 g of soil using a hexadecyltrimethyl ammonium bromide (CTAB), phenol-chloroform, and bead-beating protocol.…”

“…Local variation in topography and soil properties creates a mosaic of habitats characterized by contrasting ecological conditions. This makes the study setting ideal to investigate species-environment relationships and ecosystem functioning in the tundra [41][42][43].…”

Do lanthanide-dependent microbial metabolisms drive the release of REEs from weathered granites?

“…Soils have been a major focus of metagenomic studies that address microbial community composition (Diamond et al 2019), community changes over depth and time (Butterfield et al 2016; Sharrar et al 2020), biosynthetic potential (Sharrar et al 2020), microbial carbon compound processing (Woodcroft et al 2018), response to climate change perturbation (Cheng et al 2017; Viitamäki et al 2021), viral ecology (Emerson et al 2018) and many other aspects of biogeochemistry. However, microbial communities in weathered rocks - the precursors to soil - remain almost unstudied.…”