TABLE 2.

¹³C incorporation into PLFA and NLFA in tundra heath soil following incubation with added glucose, acetic acid, glycine, starch, or vanillin for 1 or 7 days

Fatty acid(s)a	13C incorporation in soil for the indicated substrate and incubation period (μg 13C mg−1 of added 13C g−1 of soil)b										Statistical significancec
	Glucose addition		Acetic acid addition		Glycine addition		Starch addition		Vanillin addition
	1 day	7 days	1 day	7 days	1 day	7 days	1 day	7 days	1 day	7 days
PLFATotal	1.48 ± 0.13	1.45 ± 0.20	2.38 ± 0.24	2.30 ± 0.47	0.92 ± 0.11	1.09 ± 0.08	0.40 ± 0.06	1.24 ± 0.04	0.32 ± 0.03	0.54 ± 0.08	S ***, T *, S×T *
NLFATotal	0.51 ± 0.06	0.26 ± 0.06	1.27 ± 0.11	0.51 ± 0.20	0.15 ± 0.02	0.08 ± 0.02	0.06 ± 0.01	0.12 ± 0.05	0.05 ± 0.01	0.08 ± 0.04	S ***, T ***, S×T ***
NLFA/PLFATotal	0.36 ± 0.03	0.19 ± 0.05	0.54 ± 0.01	0.21 ± 0.04	0.17 ± 0.01	0.08 ± 0.02	0.19 ± 0.03	0.09 ± 0.04	0.17 ± 0.03	0.12 ± 0.06	S ***, T ***, S×T ***
NLFA/PLFA18:2ω6	0.09 ± 0.01	0.08 ± 0.02	0.16 ± 0.01	0.02 ± 0.06	0.07 ± 0.07	0.09 ± 0.03	—e	—e	0.08 ± 0.01	0.07 ± 0.02	NS
NLFA/PLFA18:1ω9	1.09 ± 0.16	0.58 ± 0.07	1.65 ± 0.23	0.55 ± 0.03	0.55 ± 0.04	0.23 ± 0.03	0.31 ± 0.06	0.05 ± 0.03	0.87 ± 0.08	0.53 ± 0.14	S ***, T ***, S×T *
Fungi/bacteriaPLFA	0.30 ± 0.05	0.24 ± 0.09	0.47 ± 0.06	0.21 ± 0.16	0.006 ± 0.001	0.006 ± 0.002	0d	0.0001 ± 0.00007	0.16 ± 0.07	0.22 ± 0.16	S ***, S×T *

^aThe subscript indicates the fatty acid(s) measured.

^bValues are means ± standard errors (n = 6).

^cStatistical significance for the effects of substrate addition (S), incubation time (T), and the interaction between the two (S×T) is shown. *, P < 0.05; ***, P < 0.001; NS, P > 0.05.

^dNo ¹³C incorporation into fungi.

^eNo ¹³C in the PLFA 18:2ω6,9.