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Review article - Peer-reviewed, 2012

Simple additive effects are rare: Responses of biomass and soil processes to combined manipulations of CO2 and temperature

Dieleman, Wouter I. J.; Vicca, Sara; Dijkstra, Feike A.; Hagedorn, Frank; Hovenden, Mark J.; Larsen, Klaus S.; Morgan, Jack A.; Volder, Astrid; Beier, Claus; Dukes, Jeffrey S.; King, John; Leuzinger, Sebastian; Linder, Sune; Luo, Yiqi; Oren, Ram; de Angelis, Paolo; Tingey, David; Hoosbeek, Marcel R.; Janssens, Ivan


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.


[ CO2 ] enrichment; biomass; C sequestration; elevated temperature; manipulation experiments; multifactor experiments; nitrogen availability; soil respiration

Published in

Global Change Biology
2012, volume: 18, number: 9, pages: 2681-2693

Authors' information

Dieleman, Wouter I. J.
Vicca, Sara
University of Antwerp
Dijkstra, Feike A.
Hagedorn, Frank
Hovenden, Mark J.
Larsen, Klaus S.
Morgan, Jack A.
Volder, Astrid
Beier, Claus
Technical University of Denmark (DTU)
Dukes, Jeffrey S.
King, John
Leuzinger, Sebastian
Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre
Luo, Yiqi
University of Oklahoma
Oren, Ram
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
de Angelis, Paolo
Tingey, David
Hoosbeek, Marcel R.
Janssens, Ivan
University of Antwerp

Sustainable Development Goals

SDG13 Climate action

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