title: Turnover of recently assimilated carbon in arctic bryophytes.
abstract: Carbon (C) allocation and turnover in arctic bryophytes is largely unknown, but their response to climatic change has potentially significant impacts on arctic ecosystem C budgets. Using a combination of pulse-chase experiments and a newly developed model of C turnover in bryophytes, we show significant differences in C turnover between two contrasting arctic moss species (Polytrichum piliferum and Sphagnum fuscum). (13)C abundance in moss tissues (measured up to 1 year) and respired CO(2) (traced over 5 days) were used to parameterise the bryophyte C model with four pools representing labile and structural C in photosynthetic and stem tissue. The model was optimised using an Ensemble Kalman Filter to ensure a focus on estimating the confidence intervals (CI) on model parameters and outputs. The ratio of aboveground NPP:GPP in Polytrichum piliferum was 23% (CI 9-35%), with an average turnover time of 1.7 days (CI 1.1-2.5 days). The aboveground NPP:GPP ratio in Sphagnum fuscum was 43% (CI 19-65%) with an average turnover time of 3.1 days (CI 1.6-6.1 days). These results are the first to show differences in C partitioning between arctic bryophyte species in situ and highlight the importance of modelling C dynamics of this group separately from vascular plants for a realistic representation of vegetation in arctic C models.
authors.affiliation: School of Geosciences, University of Edinburgh, Edinburgh, UK. l.e.street@sms.ed.ac.uk
authors.forename: L E
authors.initials: LE
authors.lastname: Street
authors.forename: J A
authors.initials: JA
authors.lastname: Subke
authors.forename: M
authors.initials: M
authors.lastname: Sommerkorn
authors.forename: A
authors.initials: A
authors.lastname: Heinemeyer
authors.forename: M
authors.initials: M
authors.lastname: Williams
mesh_terms: D001110:Arctic Regions; D044002:Bryophyta / Q000033:anatomy & histology / Q000502:physiology*; D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism; D002247:Carbon Isotopes / Q000378:metabolism; D017753:Ecosystem; D007553:Isotope Labeling / Q000295:instrumentation / Q000379:methods*; D008954:Models, Biological; D010788:Photosynthesis; D013045:Species Specificity; D013548:Sweden
chemical_list: D002247:Carbon Isotopes; D002245:Carbon Dioxide; D002244:Carbon