Supporting Information
Title: Constraints to Nitrogen Acquisition of Terrestrial Plants under Elevated
CO2
Running head: Nitrogen acquisition under elevated CO2
Authors: Zhaozhong Feng1,8*, Tobias Rütting1,9, Håkan Pleijel1, Göran Wallin1, Peter
B. Reich2,7, Claudia I. Kammann3, Paul C. D. Newton4, Kazuhiko Kobayashi5,
Yunjian Luo6, Johan Uddling1*
Table S1. Aboveground litter N concentration (%) across species, N levels and
experimental years at each FACE site.
FACE name
aCO2
eCO2
Change (%)
Reference
BioCON
0.94 ± 0.04
0.84 ± 0.04
-10.6
Knops et al.
2007
CLIMAITE
0.94 ± 0.11
0.71 ± 0.10
-24.5
Larsen et al.
2011
NZ-FACE
1.53 ± 0.17
1.43 ± 0.35
-6.5
Allard et al.
2004
ORNL
0.82 ± 0.01
0.71 ± 0.01
-13.4
Finzi et al. 2007
POP-FACE
1.42 ± 0.06
1.19 ± 0.03
-16.2
Finzi et al. 2007
Duke
0.56 ± 0.03
0.53 ± 0.03
-5.4
Finzi et al. 2007
Aspen
1.11 ± 0.01
1.06 ± 0.11
-4.5
Finzi et al. 2007
References not in main reference list:
Allard, V., Newton, P.C.D., Lieffering, M., Soussana, J.F., Grieu, P. & Matthew, C.
(2004). Elevated CO2 effects on decomposition processes in a grazed
grassland. Global Change Biol., 10, 1553-1564.
Knops, J.M.H., Naeemw, S. & Reich, P.B. (2007). The impact of elevated CO2,
increased nitrogen availability and biodiversity on plant tissue quality and
decomposition. Global Change Biol., 13, 1960-1971.
Effect of elevated CO2 on [N] (%)
0
-2
-4
-6
-8
-10
Above-ground
Below-ground
Fig. S1. Effect of elevated CO2 on the N concentration ([N]) of the annual production
of above- and belowground plant parts. This analysis is based on data from the six
experiments where both above- and belowground biomass data were reported
(BioCON, Rice-FACE, Duke FACE, ORNL FACE, Aspen FACE, POP-FACE; see
Table 2). Error bars represent 95% confidence intervals (n = 141).
50
Effect of eCO2 on NPP (%)
-2
-1
BioCON_HN (4 g N m yr )
-2
-1
BioCON_LN (0 g N m yr )
-2
-1
ORNL (0 g N m yr )
-2
-1
Duke (0 g N m yr )
40
(a)
30
20
10
0
(b)
Effect of eCO2 on N
ac
(%)
60
40
20
0
-20
1
2
3
4
5
6
7
8
9
10
11
Experimental year
Fig. S2. Effect of elevated CO2 (eCO2) on (a) whole-plant net primary production
(NPP) and (b) corresponding nitrogen acquisition (Nac) in relation to the number of
years of experimental CO2 exposure at each FACE site. Annual N fertilization
amounts are given in the figure legend. Solid and dashed lines have positive and
negative slopes, respectively.
30
（ a)
Low diversity
High diversity
2
Effect of eCO on ANPP (%)
25
20
15
10
5
0
(b)
20
10
2
Effect of eCO on N
ac
(%)
30
0
-10
-20
0
2
4
6
8
10
12
Experimental year
Fig. S3. Effect of elevated CO2 (eCO2) on (a) aboveground net primary production
(ANPP) and (b) corresponding nitrogen acquisition (Nac) in relation to the number of
years of experimental CO2 exposure in grassland ecosystems with low diversity
(BioCON sub-plots with 1 and 4 species; Swiss-FACE) and high diversity (BioCON
subplots with 9 and 16 species; GiFACE; NZ-FACE).