Long-term macronutrient stoichiometry of UK ombrotrophic peatlands

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Abstract

In this paper we report newdata on peat carbon (C), nitrogen (N) and phosphorus (P) concentrations and accu- mulation rates for 15 sites in the UK. Concentrations of C,Nand Pmeasured in peat fromfive ombrotrophic blan- ket mires, spanning 4000–10,000 years to present were combinedwith existing nutrient data from ten Scottish ombrotrophic peat bogs to provide the first UK perspective on millennial scale macronutrient concentrations in ombrotrophic peats. Long-term average C, N and P concentrations (0–1.25 m) for the UK are 54.8, 1.56 and 0.039 wt%, of similar magnitude to the few published comparable sites worldwide. The uppermost peat (0– 0.2 m) is enriched in P and N (51.0, 1.86, and 0.070 wt%) relative to the deeper peat (0.5–1.25 m, 56.3, 1.39, and 0.027wt%). Long-termaverage (whole core) accumulation rates of C, N and P are 25.3±2.2 gCm−2 year−1 (mean±SE), 0.70±0.09 gNm−2 year−1 and 0.018±0.004 gPm−2 year−1, again similar to values reported elsewhere in the world. The two most significant findings are: 1) that a regression model of N concentration on P concentration and mean annual precipitation, based on global meta data for surface peat samples, can ex- plain 54% of variance in N concentration in these UK peat profiles; and 2) budget calculations for the UK peat cores yield an estimate for long-term average N-fixation of 0.8 gm−2 year−1. Our UK results, and comparison with others sites, corroborate published estimates of N storage in northern boreal peatlands through the Holocene as ranging between 8 and 15 Pg N. However, the observed correlation of N% with both mean annual precipitation and P concentration allows a potential bias in global estimates that do not take this into account.
Original languageEnglish
JournalScience of the Total Environment
Early online date17 Apr 2016
DOIs
Publication statusPublished - 2016

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