Table 2. Characterization of the sampled soil horizons.

	Number of samples	Depth (cm)	Organic C (%)	N (%)	C/N	δ13C (‰)
Organic topsoils	18	10.0 ± 1.4	21.39 ± 1.46 a	0.87 ± 0.05 a	25.58 ± 1.88 a	−27.45 ± 0.17 c
Mineral topsoils	23	12.7 ± 1.5	4.17 ± 0.56 b	0.26 ± 0.03 b	15.50 ± 0.62 b	−27.09 ± 0.21 c
Mineral subsoils	29	40.6 ± 4.0	1.27 ± 0.17 c	0.10 ± 0.01 c	11.89 ± 0.49 c	−26.08 ± 0.27 b
Cryoturbated	27	46.4 ± 3.6	6.48 ± 0.92 b	0.37 ± 0.04 b	16.53 ± 0.66 b	−27.12 ± 0.17 c
Permafrost	22	89.3 ± 6.2	1.43 ± 0.44 c	0.09 ± 0.02 c	12.02 ± 1.30 c	−24.75 ± 0.52 a

Different letters indicate significant differences between horizon classes at p < 0.05. For data on individual sampling sites see Supplementary Table S1.