Fig. 3: Effects of drought on the potential enzymatic activity in soil.

Colour indicates soil treatment (control = grey, 1 year = light blue, 10 years = blue). Top graphs show the potential enzymatic activities of all measured enzymes, grouped for C-, N-, and P- and S-cycle-related enzymes (for full description of enzymes see Supplementary Table 1). C-cycle enzymes all show a similar trend, where 10 years have similar values to the control, and the 1 year is always different (only statistically significant in XYL: F-value = 6.68, p = 0.016, n = 4; and partially significant in BG: F-value = 3.2, p = 0.089, n = 4). N-cycle enzymes show different responses of the 10-year treatment, where, in two enzymes both drought treatments show a decrease (END: F-value = 4.9, p = 0.036, n = 4; LAP: F-value = 14.58, p = 0.0015, n = 4), and in the other two only the 1-year treatment shows decreased values, while 10 years show values similar to control (only significant in TAP: F-value = 18.79, p < 0.001, n = 4). P- and S-cycle enzymes show the same trend where both drought plots are significantly different from the control (PHOS: F-value = 6.53, p = 0.018, n = 4; SULF: F-value = 14.75, p = 0.0014, n = 4). Stars represent significant differences with the Tukey HSD post hoc test while a dot represents partially significant values (p < 0.1). Bottom left panel shows the NMDS of potential enzymatic activities for the year 2017, with a clear separation between all treatments (R² = 0.58, p = 0.0003, n = 4, stress = 0.13). The bottom right panel represents acquisition strategies (stoichiometric ratios of the potential enzymatic activities), where a similar trend was found for all the ratios, although only statistically significant in C:P and N:P (respectively, F-value = 14.8, p = 0.001, n = 4; F-value = 8.6, p = 0.008, n = 4). Letters represent results from two-sided Tukey HSD post hoc test. Box centre line represents median, box limits the upper and lower quartiles, whiskers the 1.5x interquartile range, while separated points represent outliers. The sample size ‘n’ represents biologically independent samples.