Abstract
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 language | English |
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Pages (from-to) | 470-478 |
Number of pages | 9 |
Journal | New Phytologist |
Volume | 218 |
Issue number | 2 |
Early online date | 3 Feb 2018 |
DOIs | |
Publication status | Published - 30 Apr 2018 |
Bibliographical note
Funded by Scottish Government Rural and Environment Science and Analytical Services DivisionKeywords
- Journal Article
- bryophytes
- C : N ratio
- carbon pool
- community composition
- litter decomposition
- nitrogen pool
- nitrogen saturation
- Racomitrium heath