Table 1.

(a) Means and SD of total biomass, species number, and biomass‐weighted mean 1C‐values of the subplots according to nutrient treatment. (b) Treatment contrasts and ANOVA statistical output testing the effect of nitrogen (N) and phosphorus (P) and their interaction (N : P) on subplot total biomass‐weighted 1C‐values of subplots. The estimated coefficients in the second column show the effects of N application (i.e. without P), the effects of P application (i.e. without N), and the effects when both are applied on a subplot, where the reference level is no application of N or P (i.e. control). (c) Linear mixed effect model significance (P‐value) showing the influence of nutrients on biomass‐weighted mean 1C‐value

(a) Treatment	n	Total biomass (g)	Species no.	Biomass‐weighted mean 1C‐value (pg)
Control	12	31.71 ± 4.27	39 ± 4.2	3.99 ± 0.37
N	11	34.47 ± 3.9	31 ± 5.6	3.87 ± 0.51
P	16	44.49 ± 11.75	32 ± 4.2	4.17 ± 0.44
N + P	25	58.36 ± 11.64	20 ± 5.5	5.40 ± 0.52

(b)
	Estimate	Standard error	t‐value	Pr(> |t|)	ANOVA	df	F‐value	P‐value
Intercept	3.984	0.140	28.374	< 0.00001	Intercept	1, 60	5639.792	< 0.0001
N	−0.110	0.203	−0.543	0.58900	N	1, 60	47.589	< 0.0001
P	0.164	0.188	0.869	0.38800	P	1, 60	46.97	< 0.0001
N : P	1.331	0.257	5.178	< 0.00001	N : P	1, 60	26.816	< 0.0001

(c) Nutrient	P‐value
Si	0.0299
Na and Mg	0.1367
K	0.9221
P	< 0.0001
NO 3	< 0.0001
NH 4	< 0.0001

Significant parameters are in bold.