TABLE 1.

Comparative table on the main aspects of Nash et al. (2018) and this study.

	Study aspects	Nash et al., 2018	This study
Metagenomic soil samples	Number of samples	70	65
	Studied proglacial systems	Midtre Lovénbreen, Storglaciären, and Rabots glacier forefields; and the proglacial field of the Greenland ice sheet in proximity of point 601	Midtre Lovénbreen and Storglaciären forefields; and the proglacial field of the Greenland ice sheet in proximity of point 601 (i.e., same samples as collected, and sequenced from Nash et al., 2018)
Geochemistry	Analyzed variables	TOC and TN	TOC and TN (data from Nash et al., 2018)
Bioinformatics	Read assembly	SPADES on each forefield dataset separately	MEGAHIT on all forefield datasets together
	Gene and taxon annotation	BLAST + MEGAN	Diamond + LongMeta
Study aims	Taxon and functional association with soil developmental stages	No	Yes
	Functional characterization	nif genes	Functional trends along different developmental soil stages with a focus on genes involved in nitrogen fixation (i.e., nif genes) and rock weathering phenomena (i.e., obcA genes, genes involved in cyanide and siderophore synthesis)
	Taxon characterization	Diazotrophs present in the different proglacial systems	Taxonomic trends along different developmental soil stages

TN, total nitrogen; TOC, total organic carbon.