Editing Prairie (section)

== Formation ==
[[File:Midewin1.JPG|thumb|Tallgrass prairie flora ([[Midewin National Tallgrass Prairie]])]]
The formation of the [[Canadian Prairies]] started with the uplift of the [[Rocky Mountains]] near [[Alberta]]. The mountains created a [[rain shadow]] which resulted in lower precipitation rates downwind.<ref>{{Cite web|url=https://www.atmos.washington.edu/1998Q4/211/group6.htm|title=East Coast|website=www.atmos.washington.edu|access-date=2018-06-12|archive-date=2018-06-12|archive-url=https://web.archive.org/web/20180612211447/https://www.atmos.washington.edu/1998Q4/211/group6.htm|url-status=dead}}</ref>

The [[parent material]] of most prairie soil was distributed during the [[Quaternary glaciation|last glacial advance]] that began about 110,000 years ago. The glaciers expanding southward scraped the landscape, picking up geologic material and leveling the terrain. As the glaciers retreated about 10,000 years ago, they deposited this material in the form of [[till]]. Wind-based [[loess]] deposits also form an important parent material for prairie soils.<ref>{{cite journal|last=Hole|first=F.D.|author2=G. Nielsen|title=Soil genesis under prairie|journal=Proceedings of a Symposium on Prairie and Prairie Restoration|year=1968}}</ref>

Tallgrass prairie evolved over tens of thousands of years with the disturbances of grazing and fire. Native [[ungulate]]s such as [[bison]], [[elk]], and [[white-tailed deer]] roamed the expansive, diverse grasslands before [[European colonization of the Americas]].<ref>Dinsmore, James and Muller, Mark. (Illustrator) ''A Country So Full of Game: The Story of Wildlife in Iowa,'' Burr Oak Series. April 1994.</ref> For 10,000-20,000 years, native people used fire annually as a tool to assist in hunting, transportation, and safety.<ref>William J. McShea (Editor), William M. Healy (Editor) ''Oak Forest Ecosystems: Ecology and Management for Wildlife'', The Johns Hopkins University Press; 1st edition (October 21, 2003)</ref> Evidence of ignition sources of fire in the tall grass prairie are overwhelmingly human as opposed to lightning.<ref>Abrams, Marc D. "Native Americans as active and passive promoters of mast and fruit trees in the eastern USA ", ''The Holocene'', Vol. 18, No. 7, 1123-1137 (2008)</ref> Humans, and grazing animals, were active participants in the process of prairie formation and the establishment of the diversity of [[graminoid]] and [[forb]]s species. Fire has the effect on prairies of removing [[tree]]s, clearing dead plant matter, and changing the availability of certain nutrients in the soil from the ash produced. Fire kills the [[vascular tissue]] of trees, but not prairie species, as up to 75% (depending on the species) of the total plant [[biomass]] is below the soil surface and will re-grow from its deep (upwards of 20 feet<ref name=weaver1968>{{cite book |last=Weaver |first=J. E. |date=1968 |title=Prairie Plants and Their Environment |url=http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1007&context=agronweaver |publisher=University of Nebraska |author-link=John Ernest Weaver }}</ref>) [[root]]s. Without [[Disturbance (ecology)|disturbance]], trees will encroach on a grassland and cast shade, which suppresses the [[understory]]. Prairie and widely spaced [[oak]] trees evolved to coexist in the [[oak savanna]] ecosystem.<ref>Thompson, Janette R. ''Prairies, Forests, and Wetlands: The Restoration of Natural Landscape Communities in Iowa'' Burr Oak Series. University Of Iowa Press; 1 edition (June 1, 1992)</ref>