Dependence of ombrotrophic peat nitrogen on phosphorus and climate

Toberman, Hannah, Tipping, Edward, Boyle, John F ORCID: 0000-0002-1172-1079, Helliwell, Rachel C, Lilly, Allan and Henrys, Peter A
(2015) Dependence of ombrotrophic peat nitrogen on phosphorus and climate. BIOGEOCHEMISTRY, 125 (1). pp. 11-20.

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Nitrogen (N) is a key, possibly limiting, nutrient in ombrotrophic peat ecosystems, and enrichment by pollutant N in atmospheric deposition (Ndₑₚ, g m⁻² a⁻¹) is of concern with regard to peatland damage. We collated data on the N content of surface (depth ≤25 cm, mean 15 cm) ombrotrophic peat (Nₛₚ) for 215 sites in the UK and 62 other sites around the world, including boreal, temperate and tropical locations (wider global data), and found Nₛₚ to range from 0.5 to 4 %. We examined the dependences of Nₛₚ on surface peat phosphorus (P) content (Pₛₚ), mean annual precipitation (MAP), mean annual temperature (MAT) and Ndₑₚ. Linear regression on individual independent variables showed highly significant (p < 0.001) correlations of Nₛₚ with Pₛₚ(r² = 0.23) and MAP (r² = 0.14), and significant (p < 0.01) but weaker correlations with MAT (r² = 0.03) and Ndₑₚ (r² = 0.03). A multiple regression model using log-transformed values explained 36 % of the variance of the UK data, 84 % of the variance of the wider global data, and 47 % of the variance of the combined data, all with high significance (p < 0.001). In all three cases, most of the variance was explained by Pₛₚ and MAP, but in view of a positive correlation between MAP and MAT for many of the sites, a role for MAT in controlling Nₛₚ cannot be ruled out. There is little evidence for an effect of Ndₑₚ on Nₛₚ. The results point to a key role of P in N fixation, and thereby C fixation, in ombrotrophic peats.

Item Type: Article
Uncontrolled Keywords: Peat, Ombrotrophic, Nitrogen, Phosphorus, Climate, Nitrogen deposition
Depositing User: Symplectic Admin
Date Deposited: 17 Mar 2017 15:11
Last Modified: 19 Jan 2023 07:09
DOI: 10.1007/s10533-015-0117-0
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