Soil [N] modulates soil C cycling in CO2-fumigated tree stands: a meta-analysis.
Under elevated atmospheric CO(2) concentrations, soil carbon (C) inputs are typically enhanced, suggesting larger soil C sequestration potential. However, soil C losses also increase and progressive nitrogen (N) limitation to plant growth may reduce the CO(2) effect on soil C inputs with time. We compiled a data set from 131 manipulation experiments, and used meta-analysis to test the hypotheses that: (1) elevated atmospheric CO(2) stimulates soil C inputs more than C losses, resulting in increasing soil C stocks; and (2) that these responses are modulated by N. Our results confirm that elevated CO(2) induces a C allocation shift towards below-ground biomass compartments. However, the increased soil C inputs were offset by increased heterotrophic respiration (Rh), such that soil C content was not affected by elevated CO(2). Soil N concentration strongly interacted with CO(2) fumigation: the effect of elevated CO(2) on fine root biomass and -production and on microbial activity increased with increasing soil N concentration, while the effect on soil C content decreased with increasing soil N concentration. These results suggest that both plant growth and microbial activity responses to elevated CO(2) are modulated by N availability, and that it is essential to account for soil N concentration in C cycling analyses.
Dieleman
W I J
WI
Department of Biology, University of Antwerp (UA), Wilrijk, Belgium. wouter.dieleman@ua.ac.be
Luyssaert
S
S
Rey
A
A
de Angelis
P
P
Barton
C V M
CV
Broadmeadow
M S J
MS
Broadmeadow
S B
SB
Chigwerewe
K S
KS
Crookshanks
M
M
Dufrêne
E
E
Jarvis
P G
PG
Kasurinen
A
A
Kellomäki
S
S
Le Dantec
V
V
Liberloo
M
M
Marek
M
M
Medlyn
B
B
Pokorný
R
R
Scarascia-Mugnozza
G
G
Temperton
V M
VM
Tingey
D
D
Urban
O
O
Ceulemans
R
R
Janssens
I A
IA
D001272:Atmosphere; D018533:Biomass; D057486:Carbon Cycle; D002245:Carbon Dioxide; D005308:Fertilizers; D058458:Nitrogen Cycle; D012987:Soil / Q000032:analysis*; D014197:Trees / Q000254:growth & development*
D005308:Fertilizers; D012987:Soil; D002245:Carbon Dioxide