title: The fate of photosynthetically-fixed carbon in Lolium perenne grassland as modified by elevated CO2 and sward management.
abstract: 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.
authors.affiliation: School of Biological Sciences, University of Wales Bangor, Robinson Building, Deiniol Road, Bangor, Gwynedd LL57 2UW, UK.
authors.forename: P W
authors.initials: PW
authors.lastname: Hill
authors.affiliation: School of Biological Sciences, University of Wales Bangor, Robinson Building, Deiniol Road, Bangor, Gwynedd LL57 2UW, UK.
authors.forename: C
authors.initials: C
authors.lastname: Marshall
authors.affiliation: School of Biological Sciences, University of Wales Bangor, Robinson Building, Deiniol Road, Bangor, Gwynedd LL57 2UW, UK.
authors.forename: G G
authors.initials: GG
authors.lastname: Williams
authors.affiliation: Federal Institute of Technology (ETH) Zurich, Institute of Plant Sciences, Experimental Station Eschikon 33, CH-8315 Lindau, Switzerland.
authors.forename: H
authors.initials: H
authors.lastname: Blum
authors.affiliation: Centre for Ecology and Hydrology, Orton Building, Deiniol Road, Bangor, Gwynedd LL57 2UP, UK.
authors.forename: H
authors.initials: H
authors.lastname: Harmens
authors.affiliation: School of the Environment and Natural Resources, University of Wales Bangor, Thoday Building, Deiniol Road, Bangor, Gwynedd LL57 2UW, UK.
authors.forename: D L
authors.initials: DL
authors.lastname: Jones
authors.affiliation: School of Biological Sciences, University of Wales Bangor, Robinson Building, Deiniol Road, Bangor, Gwynedd LL57 2UW, UK.
authors.forename: J F
authors.initials: JF
authors.lastname: Farrar
mesh_terms: 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*
chemical_list: D012987:Soil; D002245:Carbon Dioxide; D002244:Carbon; D009584:Nitrogen