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Keywords:

  • 13C;
  • Arctic;
  • carbon;
  • decomposition sequestration;
  • grass;
  • moss;
  • plant growth form

Summary

  • This study investigates the influence of vegetation composition on carbon (C) sequestration in a moss-dominated ecosystem in the Arctic.
  • A 13C labelling study in an arctic wet meadow was used to trace assimilate into C pools of differing recalcitrance within grasses and mosses and to determine the retention of C by these plant groups.
  • Moss retained 70% of assimilated 13C over the month following labelling, which represented half the growing season. By contrast, the vascular plants, comprising mostly grasses, retained only 40%. The mechanism underlying this was that moss allocated 80% of the 13C to recalcitrant C pools, a much higher proportion than in grasses (56%).
  • This method enabled elucidation of a plant trait that will influence decomposition and hence persistence of assimilated C in the ecosystem. We predict that moss-dominated vegetation will retain sequestered C more strongly than a grass-dominated community. Given the strong environmental drivers that are causing a shift from moss to grass dominance, this is likely to result in a reduction in future ecosystem C sink strength.