title: The role of mosses in carbon uptake and partitioning in arctic vegetation.
abstract: The Arctic is already experiencing changes in plant community composition, so understanding the contribution of different vegetation components to carbon (C) cycling is essential in order to accurately quantify ecosystem C balance. Mosses contribute substantially to biomass, but their impact on carbon use efficiency (CUE) - the proportion of gross primary productivity (GPP) incorporated into growth - and aboveground versus belowground C partitioning is poorly known. We used (13) C pulse-labelling to trace assimilated C in mosses (Sphagnum sect. Acutifolia and Pleurozium schreberi) and in dwarf shrub-P. schreberi vegetation in sub-Arctic Finland. Based on (13) C pools and fluxes, we quantified the contribution of mosses to GPP, CUE and partitioning. Mosses incorporated 20 ± 9% of total ecosystem GPP into biomass. CUE of Sphagnum was 68-71%, that of P. schreberi was 62-81% and that of dwarf shrub-P. schreberi vegetation was 58-74%. Incorporation of C belowground was 10 ± 2% of GPP, while vascular plants alone incorporated 15 ± 4% of their fixed C belowground. We have demonstrated that mosses strongly influence C uptake and retention in Arctic dwarf shrub vegetation. They increase CUE, and the fraction of GPP partitioned aboveground. Arctic C models must include mosses to accurately represent ecosystem C dynamics.
authors.affiliation: School of Geosciences, University of Edinburgh, Crew Building, Edinburgh, EH9 3JN, UK.
authors.forename: Lorna E
authors.initials: LE
authors.lastname: Street
authors.affiliation: Stockholm Environment Institute, University of York, Grimston House, York, YO10 5DD, UK.
authors.forename: Jens-Arne
authors.initials: JA
authors.lastname: Subke
authors.affiliation: James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, UK.
authors.forename: Martin
authors.initials: M
authors.lastname: Sommerkorn
authors.affiliation: Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK.
authors.forename: Victoria
authors.initials: V
authors.lastname: Sloan
authors.affiliation: School of Geosciences, University of Edinburgh, Crew Building, Edinburgh, EH9 3JN, UK.
authors.forename: Helene
authors.initials: H
authors.lastname: Ducrotoy
authors.affiliation: Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK.
authors.forename: Gareth K
authors.initials: GK
authors.lastname: Phoenix
authors.affiliation: School of Geosciences, University of Edinburgh, Crew Building, Edinburgh, EH9 3JN, UK.
authors.forename: Mathew
authors.initials: M
authors.lastname: Williams
mesh_terms: D001110:Arctic Regions; D018533:Biomass; D044002:Bryophyta / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism; D002247:Carbon Isotopes / Q000032:analysis / Q000378:metabolism; D017753:Ecosystem; D005387:Finland; D008954:Models, Biological
chemical_list: D002247:Carbon Isotopes; D002245:Carbon Dioxide; D002244:Carbon