Microform-scale variations in peatland permeability and their ecohydrological implications

Andy J. Baird, Alice Milner, Antony Blundell, Graeme T. Swindles, Paul J. Morris

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Abstract

1.The acrotelm-catotelm model of peatland hydrological and biogeochemical processes posits that the permeability of raised bogs is largely homogenous laterally but varies strongly with depth through the soil profile; uppermost peat layers are highly permeable while deeper layers are, effectively, impermeable.2.We measured down-core changes in peat permeability, plant macrofossil assemblages, dry bulk density and degree of humification beneath two types of characteristic peatland microform – ridges and hollows – at a raised bog in Wales. Six 14C dates were also collected for one hollow and an adjacent ridge.3.Contrary to the acrotelm-catotelm model, we found that deeper peat can be as highly permeable as near-surface peat and that its permeability can vary by more than an order of magnitude between microforms over horizontal distances of 1-5 metres.4.Our palaeo-ecological data paint a complicated picture of microform persistence. Some microforms can remain in the same position on a bog for millennia, growing vertically upwards as the bog grows. However, adjacent areas on the bog (< 10 m distant) show switches between microform type over time, indicating a lack of persistence.5.Synthesis. We suggest that the acrotelm-catotelm model should be used cautiously; spatial variations in peatland permeability do not fit the simple patterns suggested by the model. To understand how peatlands as a whole function both hydrologically and ecologically it is necessary to understand how patterns of peat physical properties and peatland vegetation develop and persist. 
Original languageEnglish
Pages (from-to)531-544
Number of pages14
JournalJournal of Ecology
Volume104
Issue number2
Early online date14 Dec 2015
DOIs
Publication statusPublished - Mar 2016

Keywords

  • acrotelm-catotelm model
  • ecological memory
  • microform
  • peatland
  • permeability
  • persistence
  • plant-soil (below-ground)
  • interactions
  • raised bog

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