Nitrogen deposition drives loss of moss cover in alpine moss-sedge heath via lowered C : N ratio and accelerated decomposition

Andrea J Britton, Ruth J Mitchell, Julia M Fisher, David J Riach, Andy F S Taylor

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)


In alpine ecosystems, nitrogen (N) deposition has been linked to plant community composition change, including loss of bryophytes and increase of graminoids. Since bryophyte growth is stimulated by increased N availability, it has been hypothesized that loss of bryophyte cover is driven by enhanced decomposition. As bryophyte mats are a significant carbon (C) store, their loss may impact C storage in these ecosystems. We used an N deposition gradient across 15 sites in the UK to examine effects of N deposition on bryophyte litter quality, decomposition and C and N stocks in Racomitrium moss-sedge heath. Increasing N deposition reduced C : N in bryophyte litter, which in turn enhanced decomposition. Soil N stocks increased significantly in response to increased N deposition, and soil C : N declined. However, depletion of the bryophyte mat and its replacement by graminoids under high N deposition was not associated with a change in total ecosystem C stocks. We conclude that decomposition processes in Racomitrium heath are very sensitive to N deposition and provide a mechanism by which N deposition drives depletion of the bryophyte mat. Nitrogen deposition did not measurably alter C stocks, but changes in soil N stocks and C : N suggest the ecosystem is becoming N saturated.

Original languageEnglish
Pages (from-to)470-478
Number of pages9
JournalNew Phytologist
Issue number2
Early online date3 Feb 2018
Publication statusPublished - 30 Apr 2018

Bibliographical note

Funded by Scottish Government Rural and Environment Science and Analytical Services Division


  • Journal Article
  • bryophytes
  • C : N ratio
  • carbon pool
  • community composition
  • litter decomposition
  • nitrogen pool
  • nitrogen saturation
  • Racomitrium heath


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