Fig. 2: Radiocarbon activity of bulk SOC and PyC.

a Bulk soil and PyC_HyPy F¹⁴C between northern and southern sites and (b), for individual northern and (c), southern sites of 0–15 cm soil depth. The landscape gradients are indicated with bottom (B), slope (S) and top (T) sites (see methods). Significant differences between northern and southern sites (p < 0.001, two-sided Students’s t test) are indicated by asterisk and for bulk SOC (small letters) and PyC_HyPy (capital letters) between the individual sites within northern and southern sites (p < 0.05, tested with an one-way analysis of variances (ANOVA) and multiple comparison with a post-hoc-test (Tukey; 95% pairwise confidence level) and Bonferroni adjustment. In (a), the bulk SOC F¹⁴C values are composed of n = 45 and n = 49 samples for northern and southern sites, respectively. For the PyC_HyPy, n = 43 for northern and n = 46 for southern sites were considered. Calibrated PyC_HyPy ages are presented in Table 1. For all individual F¹⁴C values and Δ¹⁴C values and number of samples per site (n = 5–9) see Supplementary Table 2. All boxplots show the upper and lower quantile and the median. The statistical test results are shown in Supplementary Tables 9, 10.