Controls on near-surface hydraulic conductivity in a raised bog

Morris, Paul and Baird, Andrew and Eades, Phil A. and Surridge, Benjamin William James (2019) Controls on near-surface hydraulic conductivity in a raised bog. Water Resources Research, 55 (2). pp. 1531-1543. ISSN 1944-7973

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Abstract

Shallow water tables protect northern peatlands and their important carbon stocks from aerobic decomposition. Hydraulic conductivity, K, is a key control on water tables. The controls on K, particularly in degraded and restored peatlands, remain a subject of ongoing research. We took 29 shallow (~50 cm) peat cores from an estuarine raised bog in Wales, UK. Parts of the bog are in close-to-natural condition, while other areas have undergone shallow peat cutting for fuel and drainage, followed by restoration through ditch blocking. In the laboratory we measured horizontal (Kh) and vertical (Kv) hydraulic conductivity. We fitted linear multiple regression models to describe log10-transformed Kh and Kv on the basis of simple, easy-to-measure predictors. Dry bulk density and degree of decomposition were the strongest predictors of Kh and Kv. Perhaps surprisingly, the independent effect of hummocks was to produce higher-Kv peat than in lawns; while the independent effect of restored diggings was to produce higher-K peat than in uncut locations. Our models offer high explanatory power for Kh (adjusted r2 = 0.740) and K (adjusted r2 = 0.787). Our findings indicate that generalizable predictive models of peat K, similar to pedotransfer functions for mineral soils, may be attainable. Kh and Kv possess subtly different controls that are consistent with the contrasting roles of these two properties in peatland water budgets. Our near-surface samples show no evidence for the low-K marginal peat previously observed in deeper layers at the same site, indicating that such structures may be less important than previously believed.

Item Type:
Journal Article
Journal or Publication Title:
Water Resources Research
Additional Information:
This is the peer reviewed version of the following article: Morris, P. J., Baird, A. J., Eades, P. A., & Surridge, B. W. J. ( 2019). Controls on near‐surface hydraulic conductivity in a raised bog. Water Resources Research, 55, 1531– 1543. https://doi.org/10.1029/2018WR024566 which has been published in final form at https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018WR024566 This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/2300/2312
Subjects:
ID Code:
130989
Deposited By:
Deposited On:
01 Feb 2019 09:45
Refereed?:
Yes
Published?:
Published
Last Modified:
26 Sep 2020 05:48