title: Stem girdling affects the quantity of CO2 transported in xylem as well as CO2 efflux from soil.
abstract: There is recent clear evidence that an important fraction of root-respired CO2 is transported upward in the transpiration stream in tree stems rather than fluxing to the soil. In this study, we aimed to quantify the contribution of root-respired CO2 to both soil CO2 efflux and xylem CO2 transport by manipulating the autotrophic component of belowground respiration. We compared soil CO2 efflux and the flux of root-respired CO2 transported in the transpiration stream in girdled and nongirdled 9-yr-old oak trees (Quercus robur) to assess the impact of a change in the autotrophic component of belowground respiration on both CO2 fluxes. Stem girdling decreased xylem CO2 concentration, indicating that belowground respiration contributes to the aboveground transport of internal CO2 . Girdling also decreased soil CO2 efflux. These results confirmed that root respiration contributes to xylem CO2 transport and that failure to account for this flux results in inaccurate estimates of belowground respiration when efflux-based methods are used. This research adds to the growing body of evidence that efflux-based measurements of belowground respiration underestimate autotrophic contributions.
authors.affiliation: Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Ghent University, Coupure links 653, 9000, Gent, Belgium.
authors.forename: Jasper
authors.initials: J
authors.lastname: Bloemen
authors.affiliation: Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Ghent University, Coupure links 653, 9000, Gent, Belgium.
authors.forename: Laura
authors.initials: L
authors.lastname: Agneessens
authors.affiliation: Department of Veterinary Public Health and Food Safety, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium.
authors.forename: Lieven
authors.initials: L
authors.lastname: Van Meulebroek
authors.affiliation: Department of Biology, Georgia Southern University, PO Box 8042, Statesboro, GA, 30460-8042, USA.
authors.forename: Doug P
authors.initials: DP
authors.lastname: Aubrey
authors.affiliation: Warnell School of Forestry and Natural Resources, University of Georgia, 180 East Green St, Athens, GA, 30602-2152, USA.
authors.forename: Mary Anne
authors.initials: MA
authors.lastname: McGuire
authors.affiliation: Warnell School of Forestry and Natural Resources, University of Georgia, 180 East Green St, Athens, GA, 30602-2152, USA.
authors.forename: Robert O
authors.initials: RO
authors.lastname: Teskey
authors.affiliation: Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Ghent University, Coupure links 653, 9000, Gent, Belgium.
authors.forename: Kathy
authors.initials: K
authors.lastname: Steppe
mesh_terms: D052818:Autotrophic Processes; D001530:Belgium; D001692:Biological Transport; D002245:Carbon Dioxide / Q000378:metabolism*; D019069:Cell Respiration; D005632:Fructose / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D053147:Plant Exudates / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D018547:Plant Stems / Q000033:anatomy & histology / Q000502:physiology*; D029963:Quercus / Q000033:anatomy & histology / Q000502:physiology*; D012987:Soil / Q000737:chemistry*; D013213:Starch / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism; D052584:Xylem / Q000378:metabolism*
chemical_list: D053147:Plant Exudates; D012987:Soil; D002245:Carbon Dioxide; D005632:Fructose; D013395:Sucrose; D013213:Starch; D005947:Glucose
keywords: belowground respiration; girdling; internal CO2; roots; soil CO2 efflux; xylem CO2 transport