Community structure and abundance of prokaryotic communities in arctic-alpine soils are influenced by topography and time

Several studies have shown that microbial communities in alpine soils change with elevation. For arctic-alpine soils an additional effect of microtopographic exposition has recently been shown. However, it is less known how annual weather fluctuations influence microbial communities and modulate such differences and whether this is dependent on continentality.
To investigate the prokaryotic community in response to continentality, elevation and microtopography over time, we collected soil samples over three years (2020, 2021, 2022) from two mountains in the Norwegian Scandes in late summer before the first snowfall. We covered seven elevational levels above the treeline with four microtopographic positions at each level (ridges, depressions, southern and northern exposed slopes). All study sites are equipped with permanent data loggers to document temperature and soil moisture.
Prokaryotic community structure was analysed by 16 S rRNA gene amplicon sequencing and abundance by quantitative PCR of 16S rRNA. The most abundant phyla across all study sites were Acidobacteriota, Proteobacteriota, Chloroflexi and Actinobacteriota. Strong differences in the abundance of phyla were observed between the years. Differences in community composition were assessed by Permanova and revealed that the origin of the samples from different microtopographic positions and different elevations contributed significantly to the observed variation in community composition, therewith confirming previous results. Beyond, we observed strong year-to year variation and a slight effect of continentality. Further, substantial variation was explained by combinations of these factors. We currently evaluate the role of study-site specific climatic variation on the observed differences in community structure.