Editing Megafauna (section)

===Consequences of depletion of megafauna===
Depletion of herbivorous megafauna results in increased growth of woody vegetation,<ref name=":3">{{Cite journal |last1=Malhi |first1=Yadvinder |last2=Doughty |first2=Christopher E. |last3=Galetti |first3=Mauro |last4=Smith |first4=Felisa A. |last5=Svenning |first5=Jens-Christian |last6=Terborgh |first6=John W. |date=2016-01-26 |title=Megafauna and ecosystem function from the Pleistocene to the Anthropocene |journal=Proceedings of the National Academy of Sciences |language=en |volume=113 |issue=4 |pages=838–846 |doi=10.1073/pnas.1502540113 |doi-access=free |issn=0027-8424 |pmc=4743772 |pmid=26811442}}</ref> and a consequent increase in [[wildfire]] frequency.<ref>{{Cite journal |last=Johnson |first=C.N. |date=2009-07-22 |title=Ecological consequences of Late Quaternary extinctions of megafauna |journal=Proceedings of the Royal Society B: Biological Sciences |language=en |volume=276 |issue=1667 |pages=2509–2519 |doi=10.1098/rspb.2008.1921 |issn=0962-8452 |pmc=2684593 |pmid=19324773}}</ref> Megafauna may help to suppress the growth of invasive plants.<ref>{{Cite journal |last1=Mungi |first1=Ninad Avinash |last2=Jhala |first2=Yadvendradev V. |last3=Qureshi |first3=Qamar |last4=le Roux |first4=Elizabeth |last5=Svenning |first5=Jens-Christian |date=October 2023 |title=Megaherbivores provide biotic resistance against alien plant dominance |url=https://www.nature.com/articles/s41559-023-02181-y |journal=Nature Ecology & Evolution |language=en |volume=7 |issue=10 |pages=1645–1653 |doi=10.1038/s41559-023-02181-y |issn=2397-334X}}</ref> Large herbivores and carnivores can suppress the abundance of smaller animals, resulting in their population increase when megafauna are removed.<ref name=":3" /> 

==== Effect on nutrient transport ====
Megafauna play a significant role in the lateral transport of mineral nutrients in an ecosystem, tending to translocate them from areas of high to those of lower abundance. They do so by their movement between the time they consume the nutrient and the time they release it through elimination (or, to a much lesser extent, through decomposition after death).<ref name="Wolf2013">{{cite journal|last1=Wolf|first1=A.|last2=Doughty|first2=C. E.|last3=Malhi|first3=Y.|author-link3=Yadvinder Malhi|title=Lateral Diffusion of Nutrients by Mammalian Herbivores in Terrestrial Ecosystems|journal=[[PLoS ONE]]|volume= 8|issue= 8|year= 2013|pages= e71352|doi= 10.1371/journal.pone.0071352|pmid=23951141|pmc=3739793|bibcode=2013PLoSO...871352W|doi-access=free}}</ref> In South America's [[Amazon Basin]], it is estimated that such lateral diffusion was reduced over 98% following the megafaunal extinctions that occurred roughly 12,500 years ago.<ref name = "Marshall_2013">{{cite magazine | last = Marshall | first = M. | title = Ecosystems still feel the pain of ancient extinctions | magazine = [[New Scientist]] | date = 2013-08-11 | url = https://www.newscientist.com/article/dn24026-ecosystems-still-feel-the-pain-of-ancient-extinctions.html | access-date = 2013-08-12 | archive-date = 2015-07-04 | archive-url = https://web.archive.org/web/20150704181952/https://www.newscientist.com/article/dn24026-ecosystems-still-feel-the-pain-of-ancient-extinctions.html | url-status = live }}</ref><ref name="DoughtyWolf2013">{{cite journal|last1=Doughty|first1=C. E.|last2=Wolf|first2=A.|last3=Malhi|first3=Y.|author-link3=Yadvinder Malhi|title=The legacy of the Pleistocene megafauna extinctions on nutrient availability in Amazonia|journal= [[Nature Geoscience]]|date= 2013-08-11|doi= 10.1038/ngeo1895|volume= 6|issue= 9|pages= 761–764|bibcode= 2013NatGe...6..761D}}</ref> Given that [[phosphorus]] availability is thought to limit productivity in much of the region, the decrease in its transport from the western part of the basin and from floodplains (both of which derive their supply from the uplift of the [[Andes]]) to other areas is thought to have significantly impacted the region's ecology, and the effects may not yet have reached their limits.<ref name="DoughtyWolf2013"/> In the sea, cetaceans and pinnipeds that feed at depth are thought to translocate nitrogen from deep to shallow water, enhancing [[Primary production#Oceanic production|ocean productivity]], and counteracting the activity of [[zooplankton]], which tend to do the opposite.<ref name="Roman2010">{{cite journal|last1= Roman|first1= J.|last2= McCarthy|first2= J.J.|title=The Whale Pump: Marine Mammals Enhance Primary Productivity in a Coastal Basin |journal=PLOS ONE|volume= 5|issue= 10|year= 2010|page= e13255|doi= 10.1371/journal.pone.0013255|pmc= 2952594|pmid= 20949007|bibcode= 2010PLoSO...513255R|doi-access= free}}</ref>

====Effect on methane emissions====
Large populations of megaherbivores have the potential to contribute greatly to the atmospheric concentration of [[methane]], which is an important [[greenhouse gas]]. Modern [[ruminant]] [[herbivores]] produce methane as a byproduct of [[foregut fermentation]] in digestion and release it through belching or flatulence. Today, around 20% of annual [[methane emissions]] come from livestock methane release. In the [[Mesozoic]], it has been estimated that [[sauropod]]s could have emitted 520 million tons of methane to the atmosphere annually,<ref name = "Wilkinson">{{cite journal
 | last = Wilkinson | first = D. M. |author2=Nisbet, E. G. |author3=Ruxton, G. D.
 | title = Could methane produced by sauropod dinosaurs have helped drive Mesozoic climate warmth?
 | journal = [[Current Biology]] | volume = 22 | issue = 9 | pages = R292–R293 | date = 2012-05-08
 | doi = 10.1016/j.cub.2012.03.042 | pmid = 22575462 | doi-access = free | bibcode = 2012CBio...22.R292W }}</ref> contributing to the warmer climate of the time (up to 10 °C (18 °F) warmer than at present).<ref name = "Wilkinson"/><ref name = "sauropod_methane">{{cite web | title = Dinosaur gases 'warmed the Earth' | work = BBC Nature News | date = 2012-05-07 | url = http://www.bbc.co.uk/nature/17953792 | access-date = 2012-05-08 | archive-date = 2015-12-01 | archive-url = https://web.archive.org/web/20151201084318/http://www.bbc.co.uk/nature/17953792 | url-status = live }}</ref> This large emission follows from the enormous estimated biomass of sauropods, and because methane production of individual herbivores is believed to be almost proportional to their mass.<ref name = "Wilkinson"/>

Recent studies have indicated that the extinction of megafaunal herbivores may have caused a reduction in [[atmospheric methane]]. This hypothesis is relatively new.<ref name = "Smith">{{Cite journal
  | last = Smith | first = F. A. |author2=Elliot, S. M. |author3=Lyons, S. K.
  | title = Methane emissions from extinct megafauna
  | journal = [[Nature Geoscience]] | volume = 3 | issue = 6| pages = 374–375
  | date = 2010-05-23
  | doi = 10.1038/ngeo877 |bibcode = 2010NatGe...3..374S}}</ref> One study examined the methane emissions from the [[American bison|bison]] that occupied the [[Great Plains]] of North America before contact with European settlers. The study estimated that the removal of the bison caused a decrease of as much as 2.2 million tons per year.<ref name = "Kelliher">{{Cite journal
  | last = Kelliher | first = F. M.  |author2=Clark, H.
  | title = Methane emissions from bison—An historic herd estimate for the North American Great Plains
  | journal = [[Agricultural and Forest Meteorology]] | volume = 150 | issue = 3 | pages = 473–577
  | date = 2010-03-15 | doi = 10.1016/j.agrformet.2009.11.019| bibcode =2010AgFM..150..473K}}</ref> Another study examined the change in the methane concentration in the atmosphere at the end of the [[Pleistocene epoch]] after the extinction of megafauna in the Americas. After early humans migrated to the Americas about 13,000 [[Before Present|BP]], their hunting and other associated ecological impacts led to the extinction of many megafaunal species there. Calculations suggest that this extinction decreased methane production by about 9.6 million tons per year. This suggests that the absence of megafaunal methane emissions may have contributed to the abrupt climatic cooling at the onset of the [[Younger Dryas]].<ref name = "Smith"/> The decrease in atmospheric methane that occurred at that time, as recorded in [[ice core]]s, was 2 to 4 times more rapid than any other decrease in the last half million years, suggesting that an unusual mechanism was at work.<ref name = "Smith"/>