Editing Yosemite National Park (section)

==Ecology==
{{Further|Ecology of the Sierra Nevada|List of plants of the Sierra Nevada (U.S.)}}

===Habitats===
[[File:Mule deer in Yosemite Valley.jpg|thumb|upright|[[Mule deer]] in Yosemite Valley]]
The park has an elevation range from {{convert|2127|to|13114|ft|m}} and contains five major [[life zone|vegetation zones]]: [[chaparral]] and [[oak]] woodland, [[Sierra Nevada lower montane forest|lower montane forest]], upper [[Montane ecosystems#Montane forests|montane forest]], [[Sierra Nevada subalpine zone|subalpine zone]], and [[alpine tundra|alpine]]. Of California's 7,000 plant species, approximately 50 percent occur in the Sierra Nevada and more than 20 percent within the park. The park contains suitable habitat for more than 160 rare plants, with rare local [[geology|geologic]] formations and unique [[soil]]s characterizing the restricted ranges many of these plants occupy.<ref name="naturehistory" />

With its scrubby sun-baked [[chaparral]], stately groves of pine, fir, and sequoia, and expanses of alpine woodlands and meadows, Yosemite National Park preserves a Sierra landscape as it prevailed before Euro-American settlement.<ref name="snepLateSuccessional">{{Cite book
 | first1 = Jerry F.
 | last1 = Franklin
 | first2 = Jo Ann
 | last2 = Fites-Kaufmann
 | chapter = 21: Assessment of Late-Successional Forests of the Sierra Nevada
 | year = 1996
 | pages = 627–71
 | title = Sierra Nevada Ecosystem Project. Final Report to Congress. Status of the Sierra Nevada
 | volume = II: Assessments and Scientific Basis for Management Options
 | publisher = Centers for Water and Wildland Resources, University of California
 | chapter-url = http://pubs.usgs.gov/dds/dds-43/VOL_II/VII_C21.PDF
 | isbn = 1887673016
 | access-date = December 10, 2014
 | archive-date = May 13, 2019
 | archive-url = https://web.archive.org/web/20190513155027/https://pubs.usgs.gov/dds/dds-43/VOL_II/VII_C21.PDF
 | url-status = live
 }}</ref> In contrast to surrounding lands, which have been significantly altered by logging, the park contains some {{convert|225510|acre}} of [[old-growth forest]].<ref name="1993OldGrowthEstimates">{{Cite journal
 | last1 = Bolsinger
 | first1 = Charles L.
 | last2 = Waddell
 | first2 = Karen L.
 | year = 1993
 | title = Area of old-growth forests in California, Oregon, and Washington
 | url = http://www.fs.fed.us/pnw/pubs/pnw_rb197.pdf
 | publisher = [[United States Forest Service]], Pacific Northwest Research Station
 | journal = Resource Bulletin
 | issue = 197
 | id = PNW-RB-197
 | access-date = February 10, 2009
 | archive-date = October 23, 2020
 | archive-url = https://web.archive.org/web/20201023223431/https://www.fs.fed.us/pnw/pubs/pnw_rb197.pdf
 | url-status = live
 }}</ref> Taken together, the park's varied [[habitat (ecology)|habitats]] support over 250 species of [[vertebrate]]s, which include fish, amphibians, reptiles, birds, and mammals.<ref name="wildlife">{{NPS| title = Wildlife Overview | url = http://www.nps.gov/archive/yose/nature/wildlife.htm | archive-url=https://web.archive.org/web/20070127153544/http://www.nps.gov/archive/yose/nature/wildlife.htm|archive-date=January 27, 2007 | publisher = National Park Service: Yosemite Park Service | date = December 22, 2004 }}</ref>

Yosemite's western boundary has habitats dominated by [[mixed coniferous forest]]s of [[ponderosa pine]], [[sugar pine]], [[incense cedar]], [[white fir]], [[Douglas fir]], and a few stands of giant sequoia, interspersed by areas of [[California black oak|black oak]] and [[Live oak|canyon live oak]]. These habitats support relatively high wildlife diversity. Wildlife include [[American black bear|black bear]], [[coyote]], [[raccoon]], [[Kingsnake|mountain kingsnake]], [[Gilbert's skink]], [[white-headed woodpecker]], [[bobcat]], [[North American river otter|river otter]], [[gray fox]], [[red fox]], [[brown creeper]], two species of skunk, [[North American cougar|cougar]], [[spotted owl]], and bats.<ref name="wildlife"/>

At higher elevation, the coniferous forests become purer stands of [[Fir|red fir]], [[western white pine]], [[Jeffrey pine]], [[lodgepole pine]], and the occasional [[foxtail pine]]. Fewer wildlife species tend to be found in these habitats, because of their higher elevation and lower complexity. Animals include [[golden-mantled ground squirrel]], [[chickaree]], [[Fisher (animal)|fisher]], [[Steller's jay]], [[hermit thrush]], and [[American goshawk]]. Reptiles are not common, but include [[rubber boa]], [[western fence lizard]], and [[northern alligator lizard]].<ref name = "wildlife"/>

[[File:Marmota flaviventris (Yellow Bellied Marmot), Yosemite NP - Diliff.jpg|thumb|left|[[Yellow-bellied marmot|Marmot]] in [[Tuolumne Meadows]]]]
As the landscape rises, trees become smaller and more sparse, with stands broken by areas of exposed granite. These include lodgepole pine, [[whitebark pine]], and [[mountain hemlock]] that, at highest elevations, give way to vast expanses of granite as treeline is reached. The climate in these habitats is harsh and the growing season is short, but species such as [[American pika|pika]], [[yellow-bellied marmot]], white-tailed [[jackrabbit]], [[Clark's nutcracker]], and [[black rosy finch]] are adapted to these conditions. Treeless alpine habitats are favored by [[Sierra Nevada bighorn sheep]]. This species is found in the Yosemite area only around Tioga Pass, where a small, reintroduced population exists.<ref name = "wildlife"/>

At a variety of elevations, meadows provide important habitat. Animals come to feed on the green [[Poaceae|grasses]] and use the flowing and standing water found in many meadows. Predators follow these animals. The interface between meadow and forest is favored by many animal species because of the proximity of open areas for foraging and cover for protection. Species that are highly dependent upon meadow habitat include [[great grey owl]], [[willow flycatcher]], [[Yosemite toad]], and [[mountain beaver]].<ref name = "wildlife"/>

===Management issues===
[[File:YosemiteBlackBearTagged wb.jpg|thumb|A [[American black bear|black bear]] with an ear tag in Yosemite Valley]]
The black bears of Yosemite were once famous for breaking into parked cars to steal food. They were an encouraged tourist sight for many years at the park's garbage dumps, where they congregated to eat garbage, and tourists gathered to photograph them. Increasing bear/human encounters and increasing property damage led to an aggressive campaign to discourage bears from interacting with people and their stuff. The open-air dumps were closed; trash receptacles were replaced with [[bear-resistant food storage container|bear-proof]] receptacles; campgrounds were equipped with bear-proof food lockers so that people would not leave food in their vehicles. Because bears who show aggression towards people usually are destroyed, park personnel have come up with innovative ways to lead bears to associate humans and their property with experiences such as getting hit with a [[rubber bullet]]. {{as of|2001}}, about 30 bears a year were captured and [[ear tag|ear-tagged]] and their [[DNA]] sampled so that, when bear damage occurs, rangers can ascertain which bear was causing the problem.<ref>{{cite magazine | url= http://news.nationalgeographic.com/news/2001/04/0423_wirebears.html | archive-url= https://web.archive.org/web/20010430063837/http://news.nationalgeographic.com/news/2001/04/0423_wirebears.html | url-status= dead | archive-date= April 30, 2001 | title= DNA to Help Identify "Problem" Bears at Yosemite | magazine= National Geographic | date = April 23, 2001 | access-date=January 4, 2007}}</ref>{{update inline|date=November 2020}}

Despite the richness of high-quality habitats in Yosemite, the [[brown bear]], [[California condor]], and [[least Bell's vireo]] have become extinct in the park within historical time,<ref name = "snepTerrestrialVertebrates">{{Cite book | first = David M. | last = Graber | chapter = 25: Status of Terrestrial Vertebrates | year = 1996 | pages = 709–34 | title = Sierra Nevada Ecosystem Project. Final Report to Congress. Status of the Sierra Nevada Volume II: Assessments and Scientific Basis for Management Options | publisher = Centers for Water and Wildland Resources, University of California | url = http://pubs.usgs.gov/dds/dds-43/VOL_II/VII_C25.PDF | isbn = 1887673016 | access-date = December 10, 2014 | archive-date = June 20, 2020 | archive-url = https://web.archive.org/web/20200620143941/https://pubs.usgs.gov/dds/dds-43/VOL_II/VII_C25.PDF | url-status = live }}</ref> and another 37 species currently have special status under either California or federal [[endangered species]] legislation. The most serious current threats include loss of a natural fire regime, [[exotic species]], air pollution, [[habitat fragmentation]], and climate change. On a more local basis, factors such as [[road kill]]s and the availability of human food have affected some wildlife species.<ref>{{Cite web |last=Stephens |first=Tim |title=Yosemite bears and human food: Study reveals changing diets over past century |url=https://news.ucsc.edu/2014/03/yosemite-bears.html |access-date=2022-06-27 |website=UC Santa Cruz News |language=en |archive-date=June 18, 2022 |archive-url=https://web.archive.org/web/20220618204900/https://news.ucsc.edu/2014/03/yosemite-bears.html |url-status=live }}</ref><ref>{{Cite web |last=Hughes |first=Trevor |title=National park visitors leave roadkill in their wake |url=https://www.usatoday.com/story/news/nation/2013/07/27/national-park-road-kill/2587753/ |access-date=2022-06-27 |website=USA TODAY |language=en-US |archive-date=June 27, 2022 |archive-url=https://web.archive.org/web/20220627011811/https://www.usatoday.com/story/news/nation/2013/07/27/national-park-road-kill/2587753/ |url-status=live }}</ref>

[[File:Yellow star thistle.jpg|thumb|left|upright=0.6|The [[Centaurea solstitialis|yellow star thistle]] competes with Yosemite's native plants.<ref name = "exotic"/>]]
Yosemite National Park has documented the presence of more than 130 non-native plant species within park boundaries. They were introduced into Yosemite following the migration of early [[European colonization of the Americas|Euro-American]] settlers in the late 1850s. Natural and human-caused disturbances, such as wildland fires and construction activities, have contributed to a rapid increase in the spread of non-native plants. Some of these species invade and displace the native plant communities, impacting park resources. Non-native plants can bring about significant ecosystem changes by altering native plant communities and the processes that support them. Some non-native species may cause an increase in fire frequency or increase the available soil nitrogen that allow other non-native plants to establish. Many non-native species, such as [[Centaurea solstitialis|yellow star thistle]] (''Centaurea solstitialis''), are able to produce a long [[tap root]] that allows them to out-compete the native plants for available water.<ref name = "exotic">{{cite web | url= http://www.nps.gov/archive/yose/nature/veg_exotics.htm | archive-url=https://web.archive.org/web/20070102234435/http://www.nps.gov/archive/yose/nature/veg_exotics.htm|archive-date=January 2, 2007 | title= Exotic Plants | date = December 22, 2004| publisher= National Park Service: Yosemite National Park | access-date= January 4, 2007 }}</ref>

Bull thistle (''[[Cirsium vulgare]]''), common mullein (''[[Verbascum thapsus]]''), and Klamath weed (''[[Hypericum perforatum]]'') have been identified as noxious [[pest (organism)|pests]] in Yosemite since the 1940s. More recently recognized species are yellow star thistle (''Centaurea solstitialis''), sweet clover (''[[Melilot]]'' spp.), Himalayan blackberry (''[[Rubus armeniacus]]''), cut-leaved blackberry (''[[Rubus laciniatus]]'') and large periwinkle (''[[Vinca major]]'').<ref name = "exotic"/>

Increasing [[ozone]] pollution causes tissue damage to sequoia trees, making them more vulnerable to insect infestation and disease. Since the [[conifer cone|cones]] of these trees require fire-touched soil to [[germination|germinate]], historic [[Wildfire#Suppression|fire suppression]] has reduced their ability to reproduce. Planned [[prescribed fire]]s may help the germination issue.<ref>{{Cite web|title=Giant Sequoias and Fire – Sequoia & Kings Canyon National Parks (U.S. National Park Service)|url=https://www.nps.gov/seki/learn/nature/giant-sequoias-and-fire.htm|access-date=2021-04-08|website=www.nps.gov|language=en|archive-date=August 24, 2021|archive-url=https://web.archive.org/web/20210824004759/https://www.nps.gov/seki/learn/nature/giant-sequoias-and-fire.htm|url-status=live}}</ref>

===Wildfires ===
[[File:Yosemite Meadow fire, 9-7-2014.jpg|thumb|The [[Meadow Fire]] burns in Little Yosemite Valley, 2014]]
Indigenous residents intentionally set small fires in the early 1860s and before to clear the ground of brush as part as their farming practices.<ref name="Spence" /> These fires are comparable to contemporary practices such as [[controlled burn]]s that are done by the U.S. Forest Service and others. Although it was not their primary reason, Yosemite Natives helped preserve biodiversity and resilience by lighting these small fires. Native Americans used fire as an early [[wildlife management]] tool to keep certain lands clear, resulting in more food for large animals and decreasing the chance of large forest fires which that now devastate forest ecosystems.<ref name=":5">{{Cite web |last=Johnson |first=Eric Michael |title=How John Muir's Brand of Conservation Led to the Decline of Yosemite |url=https://blogs.scientificamerican.com/primate-diaries/how-john-muir-s-brand-of-conservation-led-to-the-decline-of-yosemite/ |access-date=2022-04-21 |website=Scientific American Blog Network |language=en |archive-date=May 22, 2022 |archive-url=https://web.archive.org/web/20220522193645/https://blogs.scientificamerican.com/primate-diaries/how-john-muir-s-brand-of-conservation-led-to-the-decline-of-yosemite/ |url-status=live }}</ref> Some early uncontrolled forest fires were set accidentally by the militia group led by Major John Savage when the group burned down the Ahwahneechee camp in an attempt to expel them. The house fires eventually spread to a large section of the forest and the militia group ended up having to abandon their raid to save their own camp from the conflagration.<ref name=":5" />

Forest fires clear the park of dead vegetation, making way for new growth.<ref name="Evergreen Magazine">{{cite web | url= http://evergreenmagazine.com/magazine/article/Are_there_good_forest_fires_.html | archive-url= https://web.archive.org/web/20140315012328/http://evergreenmagazine.com/magazine/article/Are_there_good_forest_fires_.html | archive-date= 2014-03-15 | title= Are There Good Forest Fires? | date = Summer 2002| publisher= Evergreen Magazine | access-date= 14 March 2014 }}</ref> Small fires damage the income generated by tourism. During late July and early August, 2018, the Valley and other sections of the park, temporarily closed due to the [[Ferguson Fire]] at its western boundary.<ref>{{Cite news|url=https://www.fresnobee.com/news/local/article215400735.html|title=Yosemite Valley will close due to fire. 'Get yourself out of here,' official says|work=fresnobee|access-date=2018-07-24|archive-date=July 24, 2018|archive-url=https://web.archive.org/web/20180724213643/https://www.fresnobee.com/news/local/article215400735.html|url-status=live}}</ref> The closing was the largest in almost thirty years.<ref>{{Cite news |url=https://www.nytimes.com/2018/07/25/us/yosemite-national-park-fire.html |title=Yosemite National Park Evacuated Amid Threat From Fire |newspaper=The New York Times |date=July 25, 2018 |access-date=2018-07-30 |last1=Branch |first1=John |last2=Medina |first2=Jennifer |last3=Fountain |first3=Henry |archive-date=July 30, 2018 |archive-url=https://web.archive.org/web/20180730140726/https://www.nytimes.com/2018/07/25/us/yosemite-national-park-fire.html |url-status=live }}</ref>