This research used the abundant moss Racomitrium lanuginosum to investigate the microbial community composition, soil bacterial recruitment, and the effect of elemental content and diazotrophic abundance on N2-fixation rates in a forest tundra and shrub tundra in Northern Quebec, Canada. A combination of amplicon sequencing of the 16S region and nifH gene was employed to characterize the overall bacterial and diazotrophic communities, respectively. Moss elemental analysis and acetylene reduction assays in moss populations were used to correlate the N2-fixation estimates with moss elemental content and abundance of diazotrophic bacteria.