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| Titel |
Long-term macronutrient stoichiometry of UK ombrotrophic peatlands |
| VerfasserIn |
Daniel Schillereff, John Boyle, Hannah Toberman, Jessica Adams, Ed Tipping |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250121944
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| Publikation (Nr.) |
 EGU/EGU2016-848.pdf |
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| Zusammenfassung |
| Ombrotrophic peatlands across northern latitudes represent a globally-important store for
carbon (C), nitrogen (N) and phosphorus (P) through the Holocene. A key characteristic of
ombrotrophic bogs is that N, P and other elements vital to their biogeochemical functioning
are almost exclusively supplied by hydrological and biological inputs from the
atmosphere. While different mechanisms regulating the atmospheric supply of N and P
and their limiting effects on bog productivity have been widely studied, limited
attention has been paid to the long-term patterns of, and controls on, macronutrient
accumulation, cycling and stoichiometry in ombrotrophic peatlands. Indeed there is a
dearth of C, N and P stoichiometric data from the UK despite decades of peatland
research.
Using data from 15 sites, we report the first estimates of millennial-scale macronutrient
concentrations and accumulation rates in UK ombrotrophic peats. Carbon, nitrogen and
phosphorus concentrations were measured on cores from five ombrotrophic blanket mires,
spanning 4000-10000 years to present, and integrated with existing nutrient profiles from
ten Scottish sites. Long-term C, N and P concentrations for the UK are 55.1, 1.55
and 0.037 wt%, similar to the few existing northern and tropical comparable sites
worldwide. The uppermost peat (0 - 0.2 m) is more enriched in P and N (51.0, 1.86, and
0.070 wt%), while the deeper peat (0.5 – 1.25 m) is more depleted (56.6, 1.39,
and 0.028 wt%). Long-term average (whole core) accumulation rates of carbon,
nitrogen and phosphorus are 25.3±2.2 gC m−2 yr−1, 0.70±0.09 gN m−2 yr−1
and 0.018±0.004 gP m−2 yr−1, again similar to values reported elsewhere in the
world.
A number of significant findings can be drawn from our results: i) N and P concentrations
in ombrotrophic peat are strongly associated, such that a regression model of N concentration
on P concentration and mean annual precipitation, based on global meta data for surface peat
samples, can explain 54% of variance in N concentration in the UK peat profiles; ii) the
patterns of long-term macronutrient stoichiometry and accumulation between sites across the
world are strikingly similar similarity, such that peats may reasonably be treated as a
single entity in global nutrient budget calculations. Our UK results corroborate
published estimates of N storage in northern boreal peatlands through the Holocene
as ranging between 8 and 17 Pg N; and iii) higher N and P concentrations in the
surface peat is a distinctive feature that remains unconvincingly explained, raising the
possibility that enhanced atmospheric supply of nutrients may impact C uptake and
burial by peat bogs and meriting particular focus from the research community. |
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