title: Recovery of ecosystem carbon fluxes and storage from herbivory.
abstract: The carbon (C) sink strength of arctic tundra is under pressure from increasing populations of arctic breeding geese. In this study we examined how CO2and CH4fluxes, plant biomass and soil C responded to the removal of vertebrate herbivores in a high arctic wet moss meadow that has been intensively used by barnacle geese (Branta leucopsis) for ca. 20 years. We used 4 and 9 years old grazing exclosures to investigate the potential for recovery of ecosystem function during the growing season (July 2007). The results show greater above- and below-ground vascular plant biomass within the grazing exclosures with graminoid biomass being most responsive to the removal of herbivory whilst moss biomass remained unchanged. The changes in biomass switched the system from net emission to net uptake of CO2(0.47 and -0.77 μmol m-2s-1in grazed and exclosure plots, respectively) during the growing season and doubled the C storage in live biomass. In contrast, the treatment had no impact on the CH4fluxes, the total litter C pool or the soil C concentration. The rapid recovery of the above ground biomass and CO2fluxes demonstrates the plasticity of this high arctic ecosystem in terms of response to changing herbivore pressure.
authors.affiliation: School of Biosciences, University of Nottingham, University Park, Nottingham, NG7 2RD UK.
authors.forename: Sofie
authors.initials: S
authors.lastname: Sjögersten
authors.affiliation: Aberdeen Centre for Environmental Sustainability (ACES), School of Biological Sciences, University of Aberdeen, Auris, 23 St. Machar Drive, Aberdeen, AB24 3UU UK.
authors.forename: René
authors.initials: R
authors.lastname: van der Wal
authors.affiliation: Arctic Centre, University of Groningen, P.O. Box 716, 9700 AS Groningen, The Netherlands.
authors.forename: Maarten J J E
authors.initials: MJ
authors.lastname: Loonen
authors.affiliation: School of Biological Sciences, University of Aberdeen, Cruickshank Building, St. Machar Drive, Aberdeen, AB24 3UU UK.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Woodin
keywords: Carbon; Geese; Herbivory; Methane; Recovery; Tundra; Vegetation