Peat

For other uses, see Peat (disambiguation).
Not to be confused with peat moss, a plant from which peat often forms or turf, the top layer of soil from which grass grows.
A lump of peat
Peat stacks in Südmoslesfehn (district of Oldenburg, Germany) in 2013
Peat gatherers at Westhay, Somerset Levels in 1905
Peat extraction in East Frisia, Germany

Peat is an accumulation of partially decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, moors, or muskegs.[1][2] Sphagnum moss, also called peat moss, is one of the most common components in peat, although many other plants can contribute. The biological features of sphagnum mosses act to create a habitat aiding peat formation, a phenomenon termed 'habitat manipulation'.[3] Soils consisting primarily of peat are known as histosols. Peat forms in wetland conditions, where flooding or stagnant water obstructs the flow of oxygen from the atmosphere, slowing the rate of decomposition.[4] Peat properties such as organic matter content and saturated hydraulic conductivity can exhibit high spatial heterogeneity.[5]

Peatlands, particularly bogs, are the primary source of peat;[6] although less common, other wetlands, including fens, pocosins and peat swamp forests, also deposit peat. Landscapes covered in peat are home to specific kinds of plants, including Sphagnum moss, ericaceous shrubs and sedges.[Notes 1] Because organic matter accumulates over thousands of years, peat deposits provide records of past vegetation and climate by preserving plant remains, such as pollen. This allows the reconstruction of past environments and the study of land-use changes.[7]

Peat is used by gardeners and for horticulture in certain parts of the world,[8] but this is being banned in some places.[9] By volume, there are about 4 trillion cubic metres of peat in the world.[10] Over time, the formation of peat is often the first step in the geological formation of fossil fuels such as coal, particularly low-grade coal such as lignite.[11] The peatland ecosystem covers 3.7 million square kilometres (1.4 million square miles)[12] and is the most efficient carbon sink on the planet,[2][13] because peatland plants capture carbon dioxide (CO2) naturally released from the peat, maintaining an equilibrium. In natural peatlands, the "annual rate of biomass production is greater than the rate of decomposition", but it takes "thousands of years for peatlands to develop the deposits of 1.5 to 2.3 m [4.9 to 7.5 ft], which is the average depth of the boreal [northern] peatlands",[2] which store around 415 gigatonnes (Gt) of carbon (about 46 times 2019 global CO2 emissions).[12] Globally, peat stores up to 550 Gt of carbon, 42% of all soil carbon, which exceeds the carbon stored in all other vegetation types, including the world's forests, although it covers just 3% of the land's surface.[14][15]

Peat is not a renewable source of energy, due to its extraction rate in industrialized countries far exceeding its slow regrowth rate of 1 mm (0.04 in) per year,[16] and as it is also reported that peat regrowth takes place only in 30–40% of peatlands.[17] Centuries of burning and draining of peat by humans has released a significant amount of CO2 into the atmosphere,[18] and much peatland restoration is needed to help limit climate change.[19]

  1. ^ Joosten, Hans; Clarke, Donal (2002). Wise Use of Mires and Peatlands: Background and Principles including a Framework for Decision-Making (PDF) (Report). Totnes, Devon. ISBN 951-97744-8-3. Archived from the original (PDF) on 2021-07-15. Retrieved 2014-02-25.
  2. ^ a b c Hugron, Sandrine; Bussières, Julie; and Rochefort, Line (2013). Tree plantations within the context of ecological restoration of peatlands: practical guide (PDF) (Report). Laval, QC, Canada: Peatland Ecology Research Group (PERG). Archived from the original (PDF) on 16 October 2017. Retrieved 22 February 2014.
  3. ^ Walker, M.D. 2019. Sphagnum; the biology of a habitat manipulator. Sicklebrook publishing, Sheffield, U.K.
  4. ^ Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Chapter 1.
  5. ^ Ahmad, Sate; Liu, Haojie; Beyer, Florian; Kløve, Bjorn; Lennartz, Bernd (25 February 2020). "Spatial heterogeneity of soil properties in relation to microtopography in a non-tidal rewetted coastal mire" (PDF). Mires and Peat. 26 (4): 1–18. doi:10.19189/MaP.2019.GDC.StA.1779.
  6. ^ Gorham, E (1957). "The development of peatlands". Quarterly Review of Biology. 32 (2): 145–66. doi:10.1086/401755. S2CID 129085635.
  7. ^ Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge. 497 pp. 323–25
  8. ^ "A growing concern: peat is bad for the planet – and for plants". The Guardian. 2021-06-06. Retrieved 2021-06-06.
  9. ^ Bek, David; Turner, Margi Lennartsson (19 May 2021). "Peat compost to be banned – luckily, green alternatives are just as good for your garden". The Conversation. Retrieved 2021-06-06.
  10. ^ World Energy Council (2007). "Survey of Energy Resources 2007" (PDF). Archived from the original (PDF) on 2008-09-10. Retrieved 2008-08-11.
  11. ^ "Is coal still being formed today?". Australian Broadcasting Corporation. 18 February 2013. Retrieved 25 October 2015.
  12. ^ a b McGrath, Matt (2020-08-10). "Warming world 'devastating' for frozen peatlands". BBC News. Retrieved 2020-08-11.
  13. ^ "Peatlands and climate change". IUCN. 2017-11-06. Retrieved 2019-08-16.
  14. ^ "Peatlands and climate change". IUCN. November 6, 2017.
  15. ^ "Climate change and deforestation threaten world's largest tropical peatland". Carbon Brief. January 25, 2018.
  16. ^ Cite error: The named reference Keddy, P.A 2010 was invoked but never defined (see the help page).
  17. ^ "Aspects of treating peat as renewable or non-renewable natural resource" (PDF). Archived from the original (PDF) on 2013-01-21. Retrieved 2012-09-09.
  18. ^ "The History of Domestic Peat Fuel Exploitation in Relation to Carbon & Climate Change". UKEconet-Wildtrack Publishing. Retrieved 2021-06-06.
  19. ^ "How scientists are restoring boreal peatlands to help keep carbon in the ground". World Economic Forum. 20 April 2021. Retrieved 2021-06-06.


Cite error: There are <ref group=Notes> tags on this page, but the references will not show without a {{reflist|group=Notes}} template (see the help page).