TY - JOUR
T1 - Soil respiration is stimulated by elevated CO2 and reduced by summer drought
T2 - three years of measurements in a multifactor ecosystem manipulation experiment in a temperate heathland (CLIMAITE)
AU - Selsted, Merete Bang
AU - van der Linden, Leon
AU - Ibrom, Andreas
AU - Michelsen, Anders
AU - Larsen, Klaus Steenberg
AU - Pedersen, Jane
AU - Mikkelsen, Teis Nørgaard
AU - Pilegaard, Kim
AU - Beier, Claus
AU - Ambus, Per Lennart
PY - 2012/4
Y1 - 2012/4
N2 - This study investigated the impact of predicted future climatic and atmospheric conditions on soil respiration (R S) in a Danish Calluna-Deschampsia-heathland. A fully factorial in situ experiment with treatments of elevated atmospheric CO 2 (+130 ppm), raised soil temperature (+0.4 °C) and extended summer drought (5-8% precipitation exclusion) was established in 2005. The average R S, observed in the control over 3 years of measurements (1.7 μmol CO 2 m -2 sec -1), increased 38% under elevated CO 2, irrespective of combination with the drought or temperature treatments. In contrast, extended summer drought decreased R S by 14%, while elevated soil temperature did not affect R S overall. A significant interaction between elevated temperature and drought resulted in further reduction of R S when these treatments were combined. A detailed analysis of short-term R S dynamics associated with drought periods showed that R S was reduced by ~50% and was strongly correlated with soil moisture during these events. Recovery of R S to pre-drought levels occurred within 2 weeks of rewetting; however, unexpected drought effects were observed several months after summer drought treatment in 2 of the 3 years, possibly due to reduced plant growth or changes in soil water holding capacity. An empirical model that predicts R S from soil temperature, soil moisture and plant biomass was developed and accounted for 55% of the observed variability in R S. The model predicted annual sums of R S in 2006 and 2007, in the control, were 672 and 719 g C m -2 y -1, respectively. For the full treatment combination, i.e. the future climate scenario, the model predicted that soil respiratory C losses would increase by ~21% (140-150 g C m -2 y -1). Therefore, in the future climate, stimulation of C storage in plant biomass and litter must be in excess of 21% for this ecosystem to not suffer a reduction in net ecosystem exchange.
AB - This study investigated the impact of predicted future climatic and atmospheric conditions on soil respiration (R S) in a Danish Calluna-Deschampsia-heathland. A fully factorial in situ experiment with treatments of elevated atmospheric CO 2 (+130 ppm), raised soil temperature (+0.4 °C) and extended summer drought (5-8% precipitation exclusion) was established in 2005. The average R S, observed in the control over 3 years of measurements (1.7 μmol CO 2 m -2 sec -1), increased 38% under elevated CO 2, irrespective of combination with the drought or temperature treatments. In contrast, extended summer drought decreased R S by 14%, while elevated soil temperature did not affect R S overall. A significant interaction between elevated temperature and drought resulted in further reduction of R S when these treatments were combined. A detailed analysis of short-term R S dynamics associated with drought periods showed that R S was reduced by ~50% and was strongly correlated with soil moisture during these events. Recovery of R S to pre-drought levels occurred within 2 weeks of rewetting; however, unexpected drought effects were observed several months after summer drought treatment in 2 of the 3 years, possibly due to reduced plant growth or changes in soil water holding capacity. An empirical model that predicts R S from soil temperature, soil moisture and plant biomass was developed and accounted for 55% of the observed variability in R S. The model predicted annual sums of R S in 2006 and 2007, in the control, were 672 and 719 g C m -2 y -1, respectively. For the full treatment combination, i.e. the future climate scenario, the model predicted that soil respiratory C losses would increase by ~21% (140-150 g C m -2 y -1). Therefore, in the future climate, stimulation of C storage in plant biomass and litter must be in excess of 21% for this ecosystem to not suffer a reduction in net ecosystem exchange.
U2 - 10.1111/j.1365-2486.2011.02634.x
DO - 10.1111/j.1365-2486.2011.02634.x
M3 - Journal article
SN - 1354-1013
VL - 18
SP - 1216
EP - 1230
JO - Global Change Biology
JF - Global Change Biology
IS - 4
ER -
