Editing North Cascades National Park (section)

===Flora===
The flora in North Cascades National Park is influenced by the great vertical relief, the amount of moisture an area receives, the slope and soil types as well as the [[fire ecology]]. This wide array of [[ecological niches]] has allowed a great biodiversity to evolve. Few other North American national parks have recorded as many [[vascular plant]] species as have been documented in North Cascades National Park. With 1,630 species documented, experts estimate adding [[non-vascular plant]]s and [[fungus|fungi]] could more than double the number of known plant species.<ref name="plants">{{cite web|title=Plants|url=https://www.nps.gov/noca/learn/nature/plants.htm|publisher=National Park Service|access-date=March 22, 2018}}</ref> 
[[File:Arctostaphylos uva-ursi 25916.JPG|thumb|left|Common bearberry (''[[Arctostaphylos uva-ursi]]'') is a plant species normally found much further north but is found at higher elevations in the park.|alt=Reddish berries growing among thick, green, paddle-shaped leaves.]]
The park contains an estimated {{convert|236000|acre|km2}} of [[old-growth forest]]s.<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}}</ref> As little of the park was previously logged, significant stands of old growth forest can be found in the valleys and lower slopes up to the timberline at {{convert|7000|ft|abbr=on}}. From the lowest valley floors to about {{convert|2000|ft|abbr=on}}, virgin stands of [[Tsuga heterophylla|western hemlock]], [[Thuja plicata|red cedar]] and [[Douglas fir]] are common. These species are heavily dependent on deep soils, and red cedars 1,000 years old and over {{convert|200|ft|abbr=on}} tall can be found on Big Beaver Creek.<ref name="lifezone">{{cite web|title=Life Zones|url=https://www.nps.gov/noca/learn/nature/life-zones.htm|publisher=National Park Service|access-date=March 23, 2018|date=August 11, 2017}}</ref><ref name="montane">{{cite web|title=Montane Forest|url=https://www.nps.gov/noca/learn/nature/bio-diversity3.htm|publisher=National Park Service|access-date=March 23, 2018|date=August 11, 2017}}</ref> These lowest elevation forests can be accessed by trails, such as the Happy Creek Forest Walk off State Route 20, the Shadows of the Sentinels at Baker Lake, Thunder Creek Trail at Diablo Lake and the Horseshoe Bend Trail from [[Washington State Route 542|State Route 542]].<ref name="lifezone"/> In openings in the forest canopy, [[Alnus rubra|red alder]] and [[Acer macrophyllum|bigleaf maple]] can be found but throughout this dense forest, ferns, shrubs and mosses abound.<ref name="montane"/>

Between {{convert|2000|and|5500|ft|abbr=on}} the forest is dominated by the [[Abies amabilis|pacific silver fir]] tree near State Route 20 at Rainy Pass. Also at this elevation, the western hemlock is replaced by the [[Tsuga mertensiana|mountain hemlock]] as a dominant species. At elevations between {{convert|4000|and|7000|ft|abbr=on}} in the [[subalpine]] zone, the forest gives way to meadows dominated by grasses and flowering plants and shrubs. Above {{convert|7000|ft|abbr=on}} lies the [[Alpine climate|alpine]] zone where few plant species survive aside from some sparse grasses, the occasional shrub and lichens.<ref name="montane"/><ref name="lifezone"/> A warming climate has led to an altitude adjustment for many flora species, with the timberline reaching {{convert|415|ft|abbr=on}} further up the mountain slopes since the 1960s.<ref name="brief">{{cite web|title=Climate Change Resource Brief|url=https://www.nps.gov/noca/learn/nature/climate-change-resource-brief.htm|publisher=National Park Service|access-date=March 29, 2018|date=January 30, 2018}}</ref>

The biodiversity of the area is threatened by climate change and invasive [[Introduced species|exotic plant]] species.<ref name="plants"/> These plants have spread across the park through the inadvertent redistribution from human activities, attaching themselves to cars and hikers. Invasive plants include the [[Centaurea diffusa|diffuse knapweed]] and [[Phalaris arundinacea|reed canary grass]].<ref name=invasive>{{cite web|title=Non-native plants|work=North Cascades National Park|publisher=National Park Service|access-date=June 6, 2012|url=http://www.nps.gov/noca/naturescience/non-native-plants.htm}}</ref> True grass species number nearly 150 in the park; half of those are considered exotic and nonnative to the ecosystem.<ref>{{cite web|title=Grasses|url=https://www.nps.gov/noca/learn/nature/grasses.htm|publisher=National Park Service|access-date=March 23, 2018|date=February 28, 2015}}</ref>

[[Pinus albicaulis|Whitebark pine]] is native to the park and grows at elevations over {{convert|5000|ft|abbr=on}} in the drier eastern region of the park.<ref name=whitebark>{{cite web|title=Whitebark Pine Resource Brief|url=https://science.nature.nps.gov/im/units/nccn/assets/docs/briefs/whitebarkpine_brief_20101129.pdf|publisher=National Park Service|access-date=June 28, 2018|archive-url=https://web.archive.org/web/20170219063730/https://science.nature.nps.gov/im/units/nccn/assets/docs/briefs/whitebarkpine_brief_20101129.pdf|archive-date=February 19, 2017|url-status=dead}}</ref> Whitebark pine is a stabilizing species for other species of high altitude flora and provides a food source for birds such as the [[Clark's nutcracker]] and mammals including [[Tamiasciurus hudsonicus|red]] and [[Douglas squirrel]]s.<ref name=whitebark/> Scientists believe that increasing temperatures will have a negative impact on the habitat necessary to support whitebark pine, and therefore impact a wide array of other species. [[Cronartium ribicola|White pine blister rust]] and [[mountain pine beetle]]s have devastated whitebark pine populations in many regions;<ref name="pine">{{cite web|title=Climate Science and Research|url=https://www.nps.gov/noca/learn/nature/climate_science.htm|publisher=National Park Service|access-date=March 29, 2018}}</ref> as of 2018, "28&nbsp;percent of whitebark pine trees are dead, 30&nbsp;percent are infected with blister rust, and 1&nbsp;percent have died from mountain pine beetles."<ref name="brief"/>