Editing Fen (section)

== Distribution and extent ==
Fens are distributed around the world, but are most frequently found at the mid-high latitudes of the Northern Hemisphere.<ref name=":7">{{Cite journal|last1=Loisel|first1=Julie|last2=Bunsen|first2=Michael|date=2020|title=Abrupt Fen-Bog Transition Across Southern Patagonia: Timing, Causes, and Impacts on Carbon Sequestration|journal=Frontiers in Ecology and Evolution|language=English|volume=8|pages=B052-0002|doi=10.3389/fevo.2020.00273|bibcode=2020AGUFMB052.0002L|issn=2296-701X|doi-access=free}}</ref><!-- This sentence is repeated. --> They are found throughout the [[Temperate climate|temperate]] zone and [[Subarctic climate|boreal]] regions, but are also present in [[tundra]] and in specific environmental conditions in other regions around the world.<ref name=":22">{{Cite book|last=Keddy|first=Paul A.|url=https://www.worldcat.org/oclc/801405617|title=Wetland ecology : principles and conservation|date=2010|publisher=Cambridge University Press|isbn=978-1-139-22365-2|edition=2nd|location=Cambridge|oclc=801405617|access-date=2021-03-20|archive-date=2022-01-12|archive-url=https://web.archive.org/web/20220112234317/https://www.worldcat.org/title/wetland-ecology-principles-and-conservation/oclc/801405617|url-status=live}}</ref><ref name=":62">{{Cite book|last=Rydin|first=Håkan|url=https://www.worldcat.org/oclc/861559248|title=The biology of peatlands|date=2013|others=J. K. Jeglum|isbn=978-0-19-150828-8|edition=Second|location=Oxford, UK|oclc=861559248|access-date=2021-03-20|archive-date=2022-01-12|archive-url=https://web.archive.org/web/20220112234317/https://www.worldcat.org/title/biology-of-peatlands/oclc/861559248|url-status=live}}</ref> In the United States, fens are most common in the Midwest and Northeast, but can be found across the country.<ref name=":4">{{Cite journal|last1=van Diggelen|first1=Rudy|last2=Middleton|first2=Beth|last3=Bakker|first3=Jan|last4=Grootjans|first4=Ab|last5=Wassen|first5=Martin|date=November 2006|title=Fens and floodplains of the temperate zone: Present status, threats, conservation and restoration|url=http://dx.doi.org/10.1111/j.1654-109x.2006.tb00664.x|journal=Applied Vegetation Science|volume=9|issue=2|pages=157–162|doi=10.1111/j.1654-109x.2006.tb00664.x|bibcode=2006AppVS...9..157V |hdl=11370/f76f9817-87e7-4764-837d-ef51703e21c8|issn=1402-2001|hdl-access=free|access-date=2021-03-20|archive-date=2022-01-12|archive-url=https://web.archive.org/web/20220112234319/https://onlinelibrary.wiley.com/doi/10.1111/j.1654-109X.2006.tb00664.x|url-status=live}}</ref> In Canada, fens are most frequent in the [[Hudson Bay Lowlands|lowlands]] near [[Hudson Bay]] and [[James Bay]], but can also be found across the country.<ref name=":62" /> Fens are also spread across the northern latitudes of Eurasia, including Britain and Ireland, as well as Japan, but east-central Europe is especially rich in fens.<ref name=":62" /><ref name=":4" /> Further south, fens are much rarer, but do exist under specific conditions. In Africa, fens have been found in the [[Okavango Delta]] in Botswana and the highland slopes in [[Lesotho]].<ref name=":62" /> Fens can also be found at the colder latitudes of the Southern Hemisphere. They are found in New Zealand and southwest Argentina, but the extent is much less than that of the northern latitudes.<ref name=":62" /><ref name=":7" /> Locally, fens are most often found at the intersection of terrestrial and aquatic ecosystems, such as the headwaters of streams and rivers.<ref name=":62" /><ref name=":02">{{Cite book|last=Mitsch|first=William J.|url=https://www.worldcat.org/oclc/78893363|title=Wetlands|date=2007|publisher=Wiley|others=James G. Gosselink|isbn=978-0-471-69967-5|edition=4th|location=Hoboken, N.J.|oclc=78893363|access-date=2021-03-20|archive-date=2022-01-12|archive-url=https://web.archive.org/web/20220112234319/https://www.worldcat.org/title/wetlands/oclc/78893363|url-status=live}}</ref>

It is estimated that there are approximately 1.1 million square kilometers of fens worldwide, but quantifying the extent of fens is difficult.<ref name=":7" /> Because wetland definitions vary regionally, not all countries define fens the same way.<ref name=":62" /> In addition, wetland data is not always available or of high quality.<ref name=":62" /> Fens are also difficult to rigidly delineate and measure, as they are located between terrestrial and aquatic ecosystems.<ref name=":62" />