Editing Greater Yellowstone Ecosystem

{{short description|Ecosystem in the Rocky Mountains}}
{{Use mdy dates|date=January 2024}}
[[File:Gibbon River at Madison in Yellowstone-750px.JPG|300px|right|thumb|Bison grazing near [[Gibbon River]] at Madison in [[Yellowstone National Park]].]]

The '''Greater Yellowstone Ecosystem''' ('''GYE''') is one of the last remaining large, nearly intact [[ecosystem]]s in the northern [[temperate zone]] of [[Earth]].{{r|ecosystem}} It is located within the northern [[Rocky Mountains]], in areas of northwestern [[Wyoming]], southwestern [[Montana]], and eastern [[Idaho]], and is about {{convert|22|e6acre}}.<ref name=":0">{{Cite news|url=https://www.tpl.org/our-work/greater-yellowstone-ecosystem#sm.000001tw1n9rvrfo8u6y3v8zmk5xa|title=Greater Yellowstone Ecosystem|work=The Trust for Public Land|access-date=2018-08-08|language=en}}</ref> [[Yellowstone National Park]] and the [[Yellowstone Caldera]] 'hotspot' are within it.{{r|ecosystem}}

The area is a flagship site among conservation groups that promote [[ecosystem management]]. It is one of the world's foremost natural laboratories in [[landscape ecology]] and [[Holocene]] [[geology]], and is a world-renowned recreational destination. It is also home to the diverse [[native plant]]s and [[animals of Yellowstone]].

==History==

[[File:Grizzly bear range expansion in Greater Yellowstone Ecosystem 1990–2018 – animated map.gif|thumb|Grizzly bear range expansion in Greater Yellowstone Ecosystem 1990–2018]]
Yellowstone National Park boundaries were drawn in 1872 with the intent to include all the known [[Geothermal areas of Yellowstone|geothermal basins in the region]].<ref>{{Cite web |date=August 21, 2020 |title=Greater Yellowstone Ecosystem |url=https://www.nps.gov/yell/learn/nature/greater-yellowstone-ecosystem.htm |access-date=2024-01-31 |website=U.S. National Park Service |language=en}}</ref> As landscape ecology considerations were not incorporated into original boundary, revisions were suggested to conform more closely to natural topographic features, such as the ridgeline of the Absaroka Range along the east boundary. In 1929, President Hoover signed the first bill changing the park's boundaries: The northwest corner now included a significant area of petrified trees; the northeast corner was defined by the watershed of Pebble Creek; the eastern boundary included the headwaters of the Lamar River and part of the watershed of the Yellowstone River. In 1932, President Hoover issued an executive order that added more than {{convert|7,000|acres}} between the north boundary and the Yellowstone River, west of Gardiner. These lands provided winter range for elk and other ungulates.<ref>{{NPS |title=Yellowstone National Park - Birth of a National Park - Boundary Adjustments |url=https://www.nps.gov/yell/learn/historyculture/yellowstoneestablishment.htm |access-date=2022-06-24 |publisher=U.S. National Park Service |language=en}}</ref> By the 1970s, the [[grizzly bear]]'s (''Ursus arctos'') range in and near the park became the first informal minimum boundary of a theoretical "Greater Yellowstone Ecosystem" that included at least {{convert|16000|km2|acre|order=flip}}. Since then, definitions of the greater ecosystem's size have steadily grown larger. A 1994 study listed the size as {{convert|76890|km2|acre|order=flip}}, while a 1994 speech by a Greater Yellowstone Coalition leader enlarged that to {{convert|80000|km2|acre|order=flip}}.

In 1985 the [[United States House of Representatives]] Subcommittees on Public Lands and National Parks and Recreation held a joint subcommittee hearing on Greater Yellowstone, resulting in a 1986 report by the [[Congressional Research Service]] outlining shortcomings in inter-agency coordination and concluding that the area's essential values were at risk.{{cn|date=January 2024}}

==Protected areas==
{{More citations needed section|date=April 2024}}
Federally managed areas within the GYE include: 
* [[United States National Park Service]] (NPS) — [[Yellowstone National Park]], [[Grand Teton National Park]], and [[John D. Rockefeller, Jr. Memorial Parkway]].
* [[United States National Forest Service]] (USFS) — [[Gallatin National Forest|Gallatin]], [[Custer National Forest|Custer]], [[Beaverhead-Deerlodge National Forest|Beaverhead-Deerlodge]], [[Caribou-Targhee National Forest|Caribou-Targhee]], [[Bridger-Teton National Forest|Bridger-Teton]], and [[Shoshone National Forest]]s
* [[United States Fish and Wildlife Service]] (USFWS) — [[National Elk Refuge]], [[Red Rock Lakes National Wildlife Refuge|Red Rock Lakes]] and [[Grays Lake National Wildlife Refuge]]s

Ten distinct [[National Wilderness Preservation System|National Wilderness Area]]s have been established within the GYE's [[United States National Forest|National Forest]]s since 1966, mandating a higher level of [[habitat]] protection than the USFS otherwise uses.

The GYE also encompasses some privately held and state lands surrounding those managed by the U.S. Government.

[[The Trust for Public Land]] has protected {{convert|67,000| acres}} over about 40 projects in the Greater Yellowstone Ecosystem.<ref name=":0" />

==Animals and plant diversity==
=== Large mammals ===
The GYE is home to some of North America's most iconic wildlife.<ref>{{Cite web |date=2022-11-03 |title=15 Facts About Our National Mammal: The American Bison {{!}} U.S. Department of the Interior |url=https://www.doi.gov/blog/15-facts-about-our-national-mammal-american-bison |access-date=2024-07-24 |website=www.doi.gov |language=en}}</ref> The ecosystem supports the largest free-roaming herds of [[American bison|American bison (Bison bison)]] on public land,<ref>{{Cite web |title=Yellowstone Bison - Yellowstone National Park (U.S. National Park Service) |url=https://www.nps.gov/yell/learn/nature/bison.htm |access-date=2024-07-24 |website=www.nps.gov |language=en}}</ref> a species central to the region's ecological balance. [[Grizzly bear|Grizzly bears]] (Ursus arctos horribilis) and [[Gray wolves|gray wolves (Canis lupus)]] are [[Apex predator|apex predators]]<ref>{{Cite journal |last1=Tallian |first1=Aimee |last2=Ordiz |first2=Andrés |last3=Metz |first3=Matthew C. |last4=Milleret |first4=Cyril |last5=Wikenros |first5=Camilla |last6=Smith |first6=Douglas W. |last7=Stahler |first7=Daniel R. |last8=Kindberg |first8=Jonas |last9=MacNulty |first9=Daniel R. |last10=Wabakken |first10=Petter |last11=Swenson |first11=Jon E. |last12=Sand |first12=Håkan |date=2017-02-08 |title=Competition between apex predators? Brown bears decrease wolf kill rate on two continents |journal=Proceedings of the Royal Society B: Biological Sciences |language=en |volume=284 |issue=1848 |pages=20162368 |doi=10.1098/rspb.2016.2368 |issn=0962-8452 |pmc=5310606 |pmid=28179516}}</ref> that play crucial roles in regulating prey populations.<ref>{{Cite journal |last1=Berger |first1=Joel |last2=Stacey |first2=Peter B. |last3=Bellis |first3=Lori |last4=Johnson |first4=Matthew P. |date=August 2001 |title=A Mammalian Predator-Prey Imbalance: Grizzly Bear and Wolf Extinction Affect Avian Neotropical Migrants |url=http://doi.wiley.com/10.1890/1051-0761(2001)011[0947:AMPPIG]2.0.CO;2 |journal=Ecological Applications |language=en |volume=11 |issue=4 |pages=947–960 |doi=10.1890/1051-0761(2001)011[0947:AMPPIG]2.0.CO;2 |issn=1051-0761|url-access=subscription }}</ref>

[[Elk]] (Cervus canadensis) are abundant and form a key component of the ecosystem, providing sustenance for predators.<ref>{{Cite journal |last1=French |first1=Steven P. |last2=French |first2=Marilynn G. |date=1990 |title=Predatory Behavior of Grizzly Bears Feeding on Elk Calves in Yellowstone National Park, 1986-88 |url=https://www.jstor.org/stable/3872937 |journal=Bears: Their Biology and Management |volume=8 |pages=335–341 |doi=10.2307/3872937 |jstor=3872937 |issn=1936-0614 |quote=We also observed black bears (Ursus americanus), coyotes (Canis latrans), and golden eagles (Aquila chrysaetos) prey on elk calves during this study.|url-access=subscription }}</ref> Other significant [[ungulate]] species include [[moose]] (Alces alces),<ref>{{Cite journal |last=Tyers |first=Daniel B. |date=2006-01-01 |title=MOOSE POPULATION HISTORY ON THE NORTHERN YELLOWSTONE WINTER RANGE |url=https://www.alcesjournal.org/index.php/alces/article/view/397 |journal=Alces: A Journal Devoted to the Biology and Management of Moose |language=en |volume=42 |pages=133–149 |issn=2293-6629}}</ref> [[pronghorn]] (Antilocapra americana),<ref>{{Cite journal |last1=White |first1=P.J. |last2=Davis |first2=Troy L. |last3=Barnowe-Meyer |first3=Kerey K. |last4=Crabtree |first4=Robert L. |last5=Garrott |first5=Robert A. |date=April 2007 |title=Partial migration and philopatry of Yellowstone pronghorn |url=https://doi.org/10.1016/j.biocon.2006.10.041 |journal=Biological Conservation |volume=135 |issue=4 |pages=502–510 |doi=10.1016/j.biocon.2006.10.041 |bibcode=2007BCons.135..502W |issn=0006-3207|url-access=subscription }}</ref> [[bighorn sheep]] (Ovis canadensis),<ref>{{Cite journal |last1=White |first1=Patrick J |last2=Lemke |first2=Thomas O |last3=Tyers |first3=Daniel B |last4=Fuller |first4=Julie A |date=2008 |title=Initial effects of reintroduced wolves Canis lupus on bighorn sheep Ovis canadensis dynamics in Yellowstone National Park |url=https://nsojournals.onlinelibrary.wiley.com/doi/full/10.2981/0909-6396%282008%2914%5B138%3AIEORWC%5D2.0.CO%3B2 |journal=Wildlife Biology |volume=14 |issue=1 |pages=138–146|doi=10.2981/0909-6396(2008)14[138:IEORWC]2.0.CO;2 }}</ref> and [[Mountain goat|mountain goats]] (Oreamnos americanus).<ref>{{Cite journal |last=Lemke |first=Thomas O. |date=June 2004 |title=Origin, expansion, and status of mountain goats in Yellowstone National Park |url=http://www.bioone.org/doi/abs/10.2193/0091-7648%282004%2932%5B532%3AOEASOM%5D2.0.CO%3B2 |journal=Wildlife Society Bulletin |language=en |volume=32 |issue=2 |pages=532–541 |doi=10.2193/0091-7648(2004)32[532:OEASOM]2.0.CO;2 |issn=0091-7648|url-access=subscription }}</ref>

===Birds===
{{See also|List of birds of Yellowstone National Park}}
The GYE is home to a variety of birds, including iconic species like [[Bald eagle|Bald Eagles]],<ref>{{Cite web |last= |first= |last2= |first2= |title=Bald Eagle - Yellowstone National Park (U.S. National Park Service) |url=https://www.nps.gov/yell/learn/nature/bald-eagle.htm |access-date=2024-07-27 |website=www.nps.gov |language=en}}</ref> [[Golden eagle|Golden Eagles]]<ref>{{Cite web |last1=Park |first1=Mailing Address: PO Box 168 Yellowstone National |last2=Us |first2=WY 82190-0168 Phone: 307-344-7381 Contact |title=Golden Eagle - Yellowstone National Park (U.S. National Park Service) |url=https://www.nps.gov/yell/learn/nature/golden-eagle.htm |access-date=2024-07-27 |website=www.nps.gov |language=en}}</ref> and [[Peregrine falcon|Peregrine Falcons]].<ref>{{Cite web |last= |first= |last2= |first2= |title=Peregrine Falcon - Yellowstone National Park (U.S. National Park Service) |url=https://www.nps.gov/yell/learn/nature/peregrine.htm |access-date=2024-07-27 |website=www.nps.gov |language=en}}</ref> [[Osprey]] populations around [[Yellowstone Lake]], have experienced declines, linked to the decrease in Cutthroat Trout.<ref>{{Cite journal |last1=Baril |first1=Lisa M. |last2=Smith |first2=Douglas W. |last3=Drummer |first3=Thomas |last4=Koel |first4=Todd M. |date=September 2013 |title=Implications of Cutthroat Trout Declines for Breeding Ospreys and Bald Eagles at Yellowstone Lake |url=http://www.bioone.org/doi/abs/10.3356/JRR-11-93.1 |journal=Journal of Raptor Research |language=en |volume=47 |issue=3 |pages=234–245 |doi=10.3356/JRR-11-93.1 |issn=0892-1016}}</ref> Several bird species act as [[keystone species]] within the GYE. For example, the [[Clark's nutcracker|Clark's Nutcracker]] plays a crucial role in the dispersal of the all-important<ref>{{Citation |last1=Buermeyer |first1=Karl |title=Case Study: Whitebark Pine in the Greater Yellowstone Ecosystem |date=2016 |work=Climate Change in Wildlands: Pioneering Approaches to Science and Management |pages=304–326 |editor-last=Hansen |editor-first=Andrew J. |url=https://doi.org/10.5822/978-1-61091-713-1_15 |access-date=2024-07-27 |place=Washington, DC |publisher=Island Press/Center for Resource Economics |language=en |doi=10.5822/978-1-61091-713-1_15 |isbn=978-1-61091-713-1 |last2=Reinhart |first2=Daniel |last3=Legg |first3=Kristin |editor2-last=Monahan |editor2-first=William B. |editor3-last=Olliff |editor3-first=S. Thomas |editor4-last=Theobald |editor4-first=David M.|url-access=subscription }}</ref> [[Pinus albicaulis|Whitebark Pine]] seeds.<ref>{{Cite journal |last1=Hutchins |first1=H. E. |last2=Lanner |first2=R. M. |date=1982-11-01 |title=The central role of Clark's nutcracker in the dispersal and establishment of whitebark pine |url=https://doi.org/10.1007/BF00384487 |journal=Oecologia |language=en |volume=55 |issue=2 |pages=192–201 |doi=10.1007/BF00384487 |pmid=28311233 |bibcode=1982Oecol..55..192H |issn=1432-1939|url-access=subscription }}</ref>

==Management by species==
Ecological management has been most often advanced through concerns over individual [[species]] rather than over broader ecological principles. Though 20 or 30 or even 50 years of information on a population may be considered long-term by some, one of the important lessons of Greater Yellowstone management is that even half a century is not long enough to give a full idea of how a species may vary in its occupation of a wild ecosystem.

The Yellowstone hot springs are important for their diversity of [[Thermophile|thermophilic]] bacteria. These bacteria have been useful in studies of the evolution of [[photosynthesis]] and as sources of thermostable [[enzyme]]s for [[molecular biology]]. Although the smell of [[sulfur]] is common and there are some sulfur fixing [[cyanobacteria]], it has been found that [[hydrogen]] is being used as an energy source by [[extremophile]] [[microbe]]s.

[[File:Current and projected Whitebark Pine distribution in YNP.jpg|thumb|right|Current (top) and projected (bottom) distribution of [[Pinus albicaulis|whitebark pine (''Pinus albicaulis'')]] in Yellowstone National Park.]]

===Flora===
{{See also|Category: Flora of the Rocky Mountains}}{{More citations needed|date=July 2024}}
Among [[native plant]]s of the GYE, [[Pinus albicaulis|whitebark pine (''Pinus albicaulis'')]] is a species of special interest, in large part because of its seasonal importance to grizzly bears,<ref>{{Cite journal |last1=Mattson |first1=David |last2=Reinhart |first2=Daniel |date=January 1994 |title=Bear Use of Whitebark Pine Seeds in North America |url=https://www.researchgate.net/publication/344047290 |journal=Conference: Proceedings-International Workshop on Subalpine Stone Pines and Their Environment: The Status of Our Knowledge}}</ref> but also because its distribution could be dramatically reduced by relatively minor [[global warming]]. In this case, researchers do not have a good long-term data set on the species, but they understand its ecology well enough to project declining future [[conservation status]].{{Citation needed|date=July 2024}} A more immediate and serious threat to whitebark pines is an introduced [[rust (fungus)|fungal rust]] disease, [[White Pine Blister Rust]] (''Cronartium ribicola''), which is causing heavy mortality in the species. Occasional resistant individuals occur, but in the short to medium term, a severe population decline is expected.{{Citation needed|date=July 2024}}

Estimates of the decline of [[Populus tremuloides|quaking aspen (''Populus tremuloides'')]] on the park's northern range since 1872 range from 50% to 95%.{{Citation needed|date=July 2024}} The decline has been linked to multiple stressors, such as defoliation by the [[Forest tent caterpillar moth|forest tent caterpillar]] (''Malacosoma disstria''), aspen bark beetles (''[[Trypophloeus populi]]'' and ''Procryphalus mucronatus''), wood-boring beetles such as the [[Saperda calcarata|poplar borer]] (''Saperda calcarata'') and the bronze poplar borer (''Agrilus liragus''),  fungal disturbances such as those by the [[Valsa sordida|Cytospora canker]] (''Valsa sordida''), and Climate change related stressors.<ref>{{Cite journal |last1=Hogg |first1=E H |last2=Brandt |first2=James P |last3=Kochtubajda |first3=B |date=2002-05-01 |title=Growth and dieback of aspen forests in northwestern Alberta, Canada, in relation to climate and insects |url=http://www.nrcresearchpress.com/doi/10.1139/x01-152 |journal=Canadian Journal of Forest Research |language=en |volume=32 |issue=5 |pages=823–832 |doi=10.1139/x01-152 |issn=0045-5067|url-access=subscription }}</ref><ref>{{Cite journal |last1=Worrall |first1=James J. |last2=Egeland |first2=Leanne |last3=Eager |first3=Thomas |last4=Mask |first4=Roy A. |last5=Johnson |first5=Erik W. |last6=Kemp |first6=Philip A. |last7=Shepperd |first7=Wayne D. |date=March 2008 |title=Rapid mortality of Populus tremuloides in southwestern Colorado, USA |url=https://doi.org/10.1016/j.foreco.2007.09.071 |journal=Forest Ecology and Management |volume=255 |issue=3–4 |pages=686–696 |doi=10.1016/j.foreco.2007.09.071 |bibcode=2008ForEM.255..686W |issn=0378-1127|url-access=subscription }}</ref><ref>{{Cite journal |last1=Worrall |first1=James J. |last2=Rehfeldt |first2=Gerald E. |last3=Hamann |first3=Andreas |last4=Hogg |first4=Edward H. |last5=Marchetti |first5=Suzanne B. |last6=Michaelian |first6=Michael |last7=Gray |first7=Laura K. |date=July 2013 |title=Recent declines of Populus tremuloides in North America linked to climate |url=https://doi.org/10.1016/j.foreco.2012.12.033 |journal=Forest Ecology and Management |volume=299 |pages=35–51 |doi=10.1016/j.foreco.2012.12.033 |bibcode=2013ForEM.299...35W |issn=0378-1127|url-access=subscription }}</ref> 

===Fauna===
{{See also|Category: Fauna of the Rocky Mountains}}{{More citations needed section|date=April 2024}}
Anecdotal information on [[grizzly bear]] abundance dates to the mid-19th century, and administrators have made informal population estimates for more than 70 years. From these sources, ecologists know the species was common in Greater Yellowstone when [[Europe]]ans arrived and that the population was not isolated before the 1930s, but is now. Researchers do not know if bears were more or less common than now.

A 1959-1970 bear study suggested a grizzly bear population size of about 176, later revised to about 229.{{r|ecosystem}} Later estimates have ranged as low as 136 and as high as 540; the most recent is a minimum estimate of 236,{{r|ecosystem}} but biologists think there may be as many as 1,000 bears in the ecosystem.<ref name="DM 2024-01-06">{{Cite news |last=Koshmrl |first=Mike |date=2024-01-06 |title=Montana to start trucking grizzlies into Yellowstone region to improve delisting prospects |url=https://dailymontanan.com/2024/01/06/montana-to-start-trucking-grizzlies-into-yellowstone-region-to-improve-delisting-prospects/ |access-date=2024-01-31 |work=Daily Montanan |language=en-US}}</ref> Although the Greater Yellowstone population is relatively close to recovery goals, the plan's definition of recovery is controversial. Thus, even though the population may be stable or possibly increasing in the short term, in the longer term, continued [[habitat loss]], climate change, and increasing [[human]] activities may well reverse the trend.{{cn|date=January 2024}}

[[Yellowstone cutthroat trout]] (''Oncorhynchus clarki bouvieri'') have suffered considerable declines since European settlement, but recently began flourishing in some areas. Especially in [[Yellowstone Lake]] itself, long-term records indicate an almost remarkable restoration of robust populations from only three decades ago when the numbers of this [[fish]] were depleted because of excessive harvest. Its current recovery, though a significant management achievement, does not begin to restore the species' historical abundance. Also, they declined because of invasive lake trout. An aggressive lake trout removal program has caused the cutthroats to rebound.

Early accounts of [[pronghorn]] (''Antilocapra americana'') in Greater Yellowstone described [[herd]]s of hundreds seen ranging through most major [[valley|river valley]]s. These populations were decimated by 1900, and declines continued among remaining herds. On the park's northern range, pronghorn declined from 500 to 700 in the 1930s to about 122 in 1968. By 1992 the herd had increased to 536.

====Gray Wolf reintroduction====
{{main|History of wolves in Yellowstone}}
The park is a commonly cited example of [[apex predator]]s affecting an ecosystem through a [[trophic cascade]].<ref>{{Cite news |last=Weston |first=Phoebe |date=2022-06-23 |title='People may be overselling the myth': should we bring back the wolf? |url=https://www.theguardian.com/environment/2022/jun/23/rebalancing-act-bringing-back-wolf-fix-broken-ecosystem-aoe |access-date=2022-06-24 |work=The Guardian |language=en}}</ref> After the reintroduction of the [[gray wolf]] in 1995, researchers noticed drastic changes occurring. [[Elk]], the primary prey of the gray wolf, became less abundant and changed their behavior, freeing riparian zones from constant grazing. The respite allowed willows and aspens to grow, creating habitat for [[North American beaver|beaver]],<ref name=LOE032015>{{cite news|title=Beyond the Headlines|url=http://loe.org/shows/segments.html?programID=15-P13-00012&segmentID=5|access-date=March 22, 2015|work=Living on Earth|date=March 20, 2015}}</ref> [[moose]], and scores of other species. In addition to the effects on prey species, the gray wolf's presence also affected the park's [[grizzly bear]] population. The bears, emerging from hibernation, chose to scavenge off wolf kills to gain needed energy and fatten up after fasting for months. Dozens of other species have been documented scavenging from wolf kills.<ref>{{Cite journal|last1=Smith|first1=Douglas W.|last2=Peterson|first2=Rolf O.|last3=Houston|first3=Douglas B.|date=2003-04-01|title=Yellowstone after Wolves|url=https://doi.org/10.1641/0006-3568(2003)053[0330:YAW]2.0.CO;2|journal=BioScience|volume=53|issue=4|pages=330–340|doi=10.1641/0006-3568(2003)053[0330:YAW]2.0.CO;2|s2cid=56277360 |issn=0006-3568|url-access=subscription}}</ref>

==See also==
*[[Ecology of the Rocky Mountains]]
*{{C|Ecology of the Rocky Mountains|Ecology of the Rocky Mountains topics}}

==References==
{{Reflist|refs=

<ref name="ecosystem">{{USGS|last=Schullery |first=Paul |url=http://biology.usgs.gov/s+t/noframe/r114.htm |title=The Greater Yellowstone Ecosystem |work=Our Living Resources |publisher=U.S. Geological Survey |date=1995 |archive-url=https://web.archive.org/web/20060927172031/http://biology.usgs.gov/s%2Bt/noframe/r114.htm |archive-date=2006-09-27 |url-status=dead }}</ref>

}}

==Further reading==
*{{cite book |last=Turner |first=Jack |title=Travels in Greater Yellowstone |location=New York |publisher=St. Martin's Press |isbn=978-0-312-26672-1 |year=2008 |url-access=registration |url=https://archive.org/details/travelsingreater00turn }}

==External links==
* [https://web.archive.org/web/20070217232330/http://www.greateryellowstone.org/ecosystem/ Greater Yellowstone Coalition: The Greater Yellowstone Ecosystem website]
* [https://web.archive.org/web/20040223212234/http://rockyweb.cr.usgs.gov/html/gye/ USGS Rocky Mountain Mapping Center: Greater Yellowstone Ecosystem]
* [http://www.ytcleanenergy.org Yellowstone-Teton Clean Energy Coalition]
* [https://web.archive.org/web/20040313183254/http://www.tpl.org/tier3_cd.cfm?content_item_id=5263&folder_id=678 The Trust for Public Land - Greater Yellowstone Ecosystem Program]

[[Category:Greater Yellowstone Ecosystem| ]]
[[Category:Ecology of the Rocky Mountains]]
[[Category:Environment of Idaho]]
[[Category:Environment of Montana]]
[[Category:Environment of Wyoming]]
[[Category:Northwestern United States]]
[[Category:Yellowstone National Park]]
[[Category:Fauna of the Rocky Mountains]]
[[Category:Flora of the Rocky Mountains]]
[[Category:Systems ecology]]