Ecological Archives E091-051-A5

**Colleen M. Iversen, Scott D. Bridgham, and Laurie E. Kellogg. 2010. Scaling plant nitrogen use and uptake efficiencies in response to nutrient addition in peatlands. Ecology 91:693–707.**

Appendix E. Nitrogen use efficiency and N response efficiency (NRE) in leaves and wood of dominant shrub species in response to nutrient addition in the bog, the intermediate fen, and the rich fen.

	n	A_N				MRT_N				NUE				N uptake efficiency				NRE
		(g new biomass· g^-1 N content·year^-1)				(years)				(g new biomass/ g N uptake)				(g N uptake· g^-1 N available·year^-1)				(g new biomass· g^-1 N available·year^-1)
		Leaves		Wood		Leaves		Wood		Leaves		Wood		Leaves		Wood		Leaves		Wood
C. calyculata
(Bog)
Control	5,5	19	± 5^a	26	± 3^a	4.4	± 1.0^a	4.7	± 0.5^a	64	± 2^a	118	± 6^b	1.8	± 0.4^a	0.9	± 0.2^b	111	± 28^a	102	± 20^a
Nitrogen	5,5	29	± 3	9	± 2***	2.5	± 0.2	11.8	± 1.4***	71	± 3	103	± 8	0.4	± 0.1**	0.1	± 0.02***	26	± 5**	9	± 2***
Phosphorus	5,5	33	± 1	28	± 4	1.8	± 0.1	3.4	± 0.3*	62	±2**	92	± 4**	0.9	± 0.1	0.3	± 0.1†	53	± 8	30	± 6
N+P	5,5	17	± 5**	9	± 1	4.3	± 1.0**	10.1	± 0.6	56	± 3*	92	± 5	0.7	± 0.2*	0.2	± 0.1***	40	± 15	22	± 5***
Alnus rugosa
(Int. fen)
Control	5,5	41	± 1^a	5	± 1^b	1		23.3	± 6.7	41	± 1^a	79	± 5^b	1.3	± 0.8^a	0.1	± 0.1^b	52	± 29^a	12	± 8^b
Nitrogen	4,4	41	± 2	6	± 2	1		16.7	± 6.7	41	± 2	68	± 4	0.8	± 0.7***	0.1	± 0.1*	30	± 24**	6	± 5*
Phosphorus	4,4	38	± 2**	8	± 1	1		9.0	± 1.4†	38	± 2**	67	± 4*	19.7	± 2.2***	1.9	± 0.6***	744	± 58***	123	± 37***
N+P	4,5	39	± 2	8	± 3	1		12.6	± 5.2	39	± 2	59	± 6	3.3	± 1.1**	0.9	± 0.4*	129	± 48†	42	± 16
Alnus rugosa
(Rich fen)
Control	3,2	42	± 1^a	23	± 2^b	1		3.3	± 0.2	42	± 1^a	76	± 12^b	0.1	± 0.1^a	0.1	± 0.1^a	6	± 3^a	4	± 3^a
Nitrogen	4,2	44	± 1	13	± 4*	1		5.8	± 2.1*	44	± 1	69	± 7	0.1	± 0.1***	0.01	± 0.001*	4	± 2**	1	± 0.2*
Phosphorus	4,4	37	± 2**	8	± 1**	1		8.0	± 1.4**	37	± 2**	56	± 2*	8.1	± 1.9***	0.9	±0.2***	291	± 61***	49	± 9***
N+P	3,2	37	± 2	5	± 0	1		13.7	± 1.7	37	± 2	63	± 5	2.1	± 1.5**	0.3	± 0.2*	73	± 50†	20	± 8

Notes: Data are mean ± 1 SE with sample size "n" (leaves, wood) in the following treatments: Control, N addition, P addition, and combined N and P addition (N+P).^†P < 0.10; *P < 0.05; **P < 0.01 and ***P < 0.001 for the effect of nutrient addition within a species and tissue type; asterisks next to the “N+P” treatment signify a significant interaction between N and P. Letters indicate differences between tissue type in the control treatment (P < 0.10) for each parameter and species. For information on abbreviations, see Table 2.

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