TY - JOUR

T1 - Simple additive effects are rare

T2 - a quantitative review of plant biomass and soil process responses to combined manipulations of CO2 and temperature

AU - Dieleman, Wouter I.J.

AU - Vicca, Sara

AU - Dijkstra, Feike A.

AU - Hagedorn, Frank

AU - Hovenden, Mark J.

AU - Larsen, Klaus Steenberg

AU - Morgan, Jack A.

AU - Volder, Astrid

AU - Beier, Claus

AU - Dukes, Jeffrey S.

AU - King, John

AU - Leuzinger, Sebastian

AU - Linder, Sune

AU - Luo, Yiqi

AU - Oren, Ram

AU - De Angelis, Paolo

AU - Tingey, David

AU - Hoosbeek, Marcel R.

AU - Janssens, Ivan A.

PY - 2012

Y1 - 2012

N2 - In recent years, increased awareness of the potential interactions between rising atmospheric CO2 concentrations ([ CO2 ]) and temperature has illustrated the importance of multifactorial ecosystem manipulation experiments for validating Earth System models. To address the urgent need for increased understanding of responses in multifactorial experiments, this article synthesizes how ecosystem productivity and soil processes respond to combined warming and [ CO2 ] manipulation, and compares it with those obtained in single factor [ CO2 ] and temperature manipulation experiments. Across all combined elevated [ CO2 ] and warming experiments, biomass production and soil respiration were typically enhanced. Responses to the combined treatment were more similar to those in the [ CO2 ]-only treatment than to those in the warming-only treatment. In contrast to warming-only experiments, both the combined and the [ CO2 ]-only treatments elicited larger stimulation of fine root biomass than of aboveground biomass, consistently stimulated soil respiration, and decreased foliar nitrogen (N) concentration. Nonetheless, mineral N availability declined less in the combined treatment than in the [ CO2 ]-only treatment, possibly due to the warming-induced acceleration of decomposition, implying that progressive nitrogen limitation (PNL) may not occur as commonly as anticipated from single factor [ CO2 ] treatment studies. Responses of total plant biomass, especially of aboveground biomass, revealed antagonistic interactions between elevated [ CO2 ] and warming, i.e. the response to the combined treatment was usually less-than-additive. This implies that productivity projections might be overestimated when models are parameterized based on single factor responses. Our results highlight the need for more (and especially more long-term) multifactor manipulation experiments. Because single factor CO2 responses often dominated over warming responses in the combined treatments, our results also suggest that projected responses to future global warming in Earth System models should not be parameterized using single factor warming experiments

AB - In recent years, increased awareness of the potential interactions between rising atmospheric CO2 concentrations ([ CO2 ]) and temperature has illustrated the importance of multifactorial ecosystem manipulation experiments for validating Earth System models. To address the urgent need for increased understanding of responses in multifactorial experiments, this article synthesizes how ecosystem productivity and soil processes respond to combined warming and [ CO2 ] manipulation, and compares it with those obtained in single factor [ CO2 ] and temperature manipulation experiments. Across all combined elevated [ CO2 ] and warming experiments, biomass production and soil respiration were typically enhanced. Responses to the combined treatment were more similar to those in the [ CO2 ]-only treatment than to those in the warming-only treatment. In contrast to warming-only experiments, both the combined and the [ CO2 ]-only treatments elicited larger stimulation of fine root biomass than of aboveground biomass, consistently stimulated soil respiration, and decreased foliar nitrogen (N) concentration. Nonetheless, mineral N availability declined less in the combined treatment than in the [ CO2 ]-only treatment, possibly due to the warming-induced acceleration of decomposition, implying that progressive nitrogen limitation (PNL) may not occur as commonly as anticipated from single factor [ CO2 ] treatment studies. Responses of total plant biomass, especially of aboveground biomass, revealed antagonistic interactions between elevated [ CO2 ] and warming, i.e. the response to the combined treatment was usually less-than-additive. This implies that productivity projections might be overestimated when models are parameterized based on single factor responses. Our results highlight the need for more (and especially more long-term) multifactor manipulation experiments. Because single factor CO2 responses often dominated over warming responses in the combined treatments, our results also suggest that projected responses to future global warming in Earth System models should not be parameterized using single factor warming experiments

KW - ABOVEGROUND BIOMASS

KW - ATMOSPHERIC CO2

KW - ATMOSPHERIC CO2 CONCENTRATIONS

KW - AVAILABILITY

KW - biomass

KW - C sequestration

KW - CO2

KW - decomposition

KW - Earth system models

KW - ECOSYSTEM

KW - ecosystem manipulation

KW - elevated temperature

KW - experiment

KW - global warming

KW - interaction

KW - LIMITATION

KW - long-term

KW - MANIPULATION

KW - manipulation experiments

KW - MANIPULATIONS

KW - MODEL

KW - MODELS

KW - multifactor

KW - multifactor experiments

KW - N availability

KW - Nitrogen

KW - nitrogen availability

KW - PLANT

KW - plant biomass

KW - potential

KW - production

KW - productivity

KW - PROGRESSIVE NITROGEN LIMITATION

KW - projections

KW - respiration

KW - RESPONSES

KW - review

KW - RISING ATMOSPHERIC CO2

KW - ROOT

KW - soil

KW - soil respiration

KW - SYSTEM

KW - temperature

KW - warming

KW - [ CO2 ] enrichment

U2 - 10.1111/j.1365-2486.2012.02745.x

DO - 10.1111/j.1365-2486.2012.02745.x

M3 - Journal article

VL - 18

SP - 2681

EP - 2693

JO - Global Change Biology

JF - Global Change Biology

SN - 1354-1013

IS - 9

ER -