The fate of photosynthetically-fixed carbon in Lolium perenne grassland as modified by elevated CO2 and sward management.
Prediction of the impact of climate change requires the response of carbon (C) flow in plant-soil systems to increased CO(2) to be understood. A mechanism by which grassland C sequestration might be altered was investigated by pulse-labelling Lolium perenne swards, which had been subject to CO(2) enrichment and two levels of nitrogen (N) fertilization for 10 yr, with (14)CO(2). Over a 6-d period 40-80% of the (14)C pulse was exported from mature leaves, 1-2% remained in roots, 2-7% was lost as below-ground respiration, 0.1% was recovered in soil solution, and 0.2-1.5% in soil. Swards under elevated CO(2) with the lower N supply fixed more (14)C than swards grown in ambient CO(2), exported more fixed (14)C below ground and respired less than their high-N counterparts. Sward cutting reduced root (14)C, but plants in elevated CO(2) still retained 80% more (14)C below ground than those in ambient CO(2). The potential for below-ground C sequestration in grasslands is enhanced under elevated CO(2), but any increase is likely to be small and dependent upon grassland management.
Hill
P W
PW
School of Biological Sciences, University of Wales Bangor, Robinson Building, Deiniol Road, Bangor, Gwynedd LL57 2UW, UK.
Marshall
C
C
School of Biological Sciences, University of Wales Bangor, Robinson Building, Deiniol Road, Bangor, Gwynedd LL57 2UW, UK.
Williams
G G
GG
School of Biological Sciences, University of Wales Bangor, Robinson Building, Deiniol Road, Bangor, Gwynedd LL57 2UW, UK.
Blum
H
H
Federal Institute of Technology (ETH) Zurich, Institute of Plant Sciences, Experimental Station Eschikon 33, CH-8315 Lindau, Switzerland.
Harmens
H
H
Centre for Ecology and Hydrology, Orton Building, Deiniol Road, Bangor, Gwynedd LL57 2UP, UK.
Jones
D L
DL
School of the Environment and Natural Resources, University of Wales Bangor, Thoday Building, Deiniol Road, Bangor, Gwynedd LL57 2UW, UK.
Farrar
J F
JF
School of Biological Sciences, University of Wales Bangor, Robinson Building, Deiniol Road, Bangor, Gwynedd LL57 2UW, UK.
D002244:Carbon / Q000032:analysis / Q000378:metabolism*; D002245:Carbon Dioxide / Q000032:analysis* / Q000378:metabolism; D017753:Ecosystem; D008129:Lolium / Q000254:growth & development / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism; D010101:Oxygen Consumption; D010788:Photosynthesis; D012987:Soil; D003313:Zea mays / Q000254:growth & development / Q000378:metabolism*
D012987:Soil; D002245:Carbon Dioxide; D002244:Carbon; D009584:Nitrogen