Editing Fen (section)

==== Rich fens ====
[[File:Extreme Rich Fen.jpg|thumb|upright=1.3|Small extreme rich fen in southwestern Minnesota. The white flowers, ''[[Parnassia glauca]]'', are a fen indicator species in Minnesota.]]
Rich fens are strongly minerotrophic; that is, a large proportion of their water comes from mineral-rich ground or surface water. Fens that are more distant from surface waters such as rivers and lakes, however, are more rich than fens that are connected.<ref name=":3" /> This water is dominated by calcium and bicarbonate, resulting in a slightly acidic to slightly basic pH characteristic of rich fens.<ref name=":6" /><ref name=":14">{{cite book |last1=Zoltai |first1=S. C. |last2=Vitt |first2=D. H. |chapter=Canadian wetlands: Environmental gradients and classification |date=1995 |doi=10.1007/978-94-011-0427-2_11 |editor=C. Max Finlayson |editor2=A. G. van der Valk |title=Classification and Inventory of the World's Wetlands |pages=131–137 |location=Dordrecht |publisher=Springer Netherlands |isbn=978-94-010-4190-4}}</ref> These conditions promote high biodiversity. Within rich fens, there is a large amount of variability. The richest fens are the extreme rich (marl) fens, where marl deposits are often build up.<ref name=":10" /> These are often pH 7 or greater.<ref name=":6" /> Rich and intermediate rich fens are generally neutral to slightly acidic, with a pH of approximately 7 to 5. Rich fens are not always very productive; at high calcium concentrations, calcium ions bind to phosphate anions, reducing the availability of phosphorus and decreasing primary production.<ref name=":23"/><ref name=":6" /> Rich bogs with limited primary production can stabilize with the accumulation of mosses and [[mycorrhiza]], which promote phosphorus cycling and can support the growth of new vegetation and bacteria.<ref name=":5" /> Brown mosses (family ''[[Amblystegiaceae]]'') and sedges (genus ''[[Carex]]'') are the dominant vegetation.<ref name=":14" /> However, an accumulation of mosses such as ''[[Sphagnum]]'' can lead to the acidification of the rich fen, potentially converting it into a poor fen.<ref>{{Cite web|title=Poor Fen - Michigan Natural Features Inventory|url=https://mnfi.anr.msu.edu/communities/description/10662/Poor-Fen|access-date=2021-05-08|website=mnfi.anr.msu.edu|archive-date=2021-05-08|archive-url=https://web.archive.org/web/20210508211654/https://mnfi.anr.msu.edu/communities/description/10662/Poor-Fen|url-status=live}}</ref> Compared to poor fens, rich fens have higher concentrations of bicarbonate, base cations (Na<sup>+</sup>, Ca<sup>2+</sup>, K<sup>+</sup>, Mg<sup>2+</sup>), and [[sulfate]].<ref name=":11" />