TY - JOUR

T1 - Interactive effects of elevated CO2, warming, and drought on photosynthesis of Deschampsia flexuosa in a temperate heath ecosystem.

AU - Albert, K. R.

AU - Ro-Poulsen, Helge

AU - Mikkelsen, T. N.

AU - Michelsen, A.

AU - Linden, L. Van der

AU - Beier, Claus

PY - 2011

Y1 - 2011

N2 - Global change factors affect plant carbon uptake in concert. In order to investigate the response directions andpotential interactive effects, and to understand the underlying mechanisms, multifactor experiments are needed.The focus of this study was on the photosynthetic response to elevated CO2 [CO2; free air CO2 enrichment(FACE)], drought (D; water-excluding curtains), and night-time warming (T; infrared-reflective curtains) ina temperate heath. A/Ci curves were measured, allowing analysis of light-saturated net photosynthesis (Pn), lightandCO2-saturated net photosynthesis (Pmax), stomatal conductance (gs), the maximal rate of Rubiscocarboxylation (Vcmax), and the maximal rate of ribulose bisphosphate (RuBP) regeneration (Jmax) along with leafd13C, and carbon and nitrogen concentration on a monthly basis in the grass Deschampsia flexuosa. Seasonaldrought reduced Pn via gs, but severe (experimental) drought decreased Pn via a reduction in photosyntheticcapacity (Pmax, Jmax, and Vcmax). The effects were completely reversed by rewetting and stimulated Pn viaphotosynthetic capacity stimulation. Warming increased early and late season Pn via higher Pmax and Jmax.Elevated CO2 did not decrease gs, but stimulated Pn via increased Ci. The T3CO2 synergistically increased plantcarbon uptake via photosynthetic capacity up-regulation in early season and by better access to water afterrewetting. The effects of the combination of drought and elevated CO2 depended on soil water availability, withadditive effects when the soil water content was low and D3CO2 synergistic stimulation of Pn after rewetting. Thephotosynthetic responses appeared to be highly influenced by growth pattern. The grass has opportunistic waterconsumption, and a biphasic growth pattern allowing for leaf dieback at low soil water availability followed byrapid re-growth of active leaves when rewetted and possibly a large resource allocation capability mediated by therhizome. This growth characteristic allowed for the photosynthetic capacity up-regulations that mediated theT3CO2 and D3CO2 synergistic effects on photosynthesis. These are clearly advantageous characteristics whenexposed to climate changes. In conclusion, after 1 year of experimentation, the limitations by low soil wateravailability and stimulation in early and late season by warming clearly structure and interact with thephotosynthetic response to elevated CO2 in this grassland species.

AB - Global change factors affect plant carbon uptake in concert. In order to investigate the response directions andpotential interactive effects, and to understand the underlying mechanisms, multifactor experiments are needed.The focus of this study was on the photosynthetic response to elevated CO2 [CO2; free air CO2 enrichment(FACE)], drought (D; water-excluding curtains), and night-time warming (T; infrared-reflective curtains) ina temperate heath. A/Ci curves were measured, allowing analysis of light-saturated net photosynthesis (Pn), lightandCO2-saturated net photosynthesis (Pmax), stomatal conductance (gs), the maximal rate of Rubiscocarboxylation (Vcmax), and the maximal rate of ribulose bisphosphate (RuBP) regeneration (Jmax) along with leafd13C, and carbon and nitrogen concentration on a monthly basis in the grass Deschampsia flexuosa. Seasonaldrought reduced Pn via gs, but severe (experimental) drought decreased Pn via a reduction in photosyntheticcapacity (Pmax, Jmax, and Vcmax). The effects were completely reversed by rewetting and stimulated Pn viaphotosynthetic capacity stimulation. Warming increased early and late season Pn via higher Pmax and Jmax.Elevated CO2 did not decrease gs, but stimulated Pn via increased Ci. The T3CO2 synergistically increased plantcarbon uptake via photosynthetic capacity up-regulation in early season and by better access to water afterrewetting. The effects of the combination of drought and elevated CO2 depended on soil water availability, withadditive effects when the soil water content was low and D3CO2 synergistic stimulation of Pn after rewetting. Thephotosynthetic responses appeared to be highly influenced by growth pattern. The grass has opportunistic waterconsumption, and a biphasic growth pattern allowing for leaf dieback at low soil water availability followed byrapid re-growth of active leaves when rewetted and possibly a large resource allocation capability mediated by therhizome. This growth characteristic allowed for the photosynthetic capacity up-regulations that mediated theT3CO2 and D3CO2 synergistic effects on photosynthesis. These are clearly advantageous characteristics whenexposed to climate changes. In conclusion, after 1 year of experimentation, the limitations by low soil wateravailability and stimulation in early and late season by warming clearly structure and interact with thephotosynthetic response to elevated CO2 in this grassland species.

U2 - 10.1093/jxb/err133

DO - 10.1093/jxb/err133

M3 - Journal article

C2 - 21586430

VL - 62

SP - 4253

EP - 4266

JO - Journal of Experimental Botany

JF - Journal of Experimental Botany

SN - 0022-0957

IS - 12

ER -