View source for Alnus rubra

{{Short description|Species of tree}}
{{Redirect|Red alder|the Southern African tree|Cunonia capensis}}
{{Speciesbox
|image=Red alder leaves.jpg
|image_caption=Red alder leaves
|status=LC
|status_system=IUCN3.1
|status_ref=<ref name=iucn>{{cite journal |author=Stritch, L. |title=''Alnus rubra'' |journal=[[The IUCN Red List of Threatened Species]] |volume=208 |at=e.T194598A2351803. |publisher=[[IUCN]] |year=2014 |doi=10.2305/IUCN.UK.2014-3.RLTS.T194598A2351803.en|doi-access=free }}</ref>
|genus=Alnus
|parent=Alnus subg. Alnus
|species=rubra
|authority=[[August Gustav Heinrich von Bongard|Bong.]]
|range_map=Alnus rubra range map.jpg
|range_map_caption=Natural range of ''Alnus rubra''
|synonyms_ref=<ref name=wcsp/>
|synonyms=*''Alnus incana'' var. ''rubra'' <small>(Bong.) Regel</small>
* ''Alnus oregana'' <small>Nutt.</small>
* ''Alnus rubra'' var. ''pinnatisecta'' <small>Starker</small>
* ''Alnus rubra'' f. ''pinnatisecta'' <small>(Starker) Rehder</small>
}}

'''''Alnus rubra''''', the '''red alder''',<ref>USDA Plants Profile: [http://plants.usda.gov/plant-profile?symbol=ALRU2 ''Alnus rubra'']</ref><ref name=BSBI07>{{BSBI 2007 |access-date=2014-10-17}}</ref>
is a [[deciduous]] [[broadleaf tree]] native to western [[North America]] ([[Alaska]], [[Yukon]], [[British Columbia]], [[Washington (state)|Washington]], [[Oregon]], [[California]], [[Idaho]] and [[Montana]]).<ref name=wcsp>[http://apps.kew.org/wcsp/namedetail.do?name_id=6584 Kew World Checklist of Selected Plant Families]</ref><ref name=bonap>[http://bonap.net/MapGallery/County/Alnus%20rubra.png Biota of North America Program, 2013 county distribution map]</ref>{{r|ubc}}

==Description==
''Alnus rubra'' is the largest species of [[alder]] in North America and one of the largest in the world, reaching heights of {{convert|20|to|30|m|ft}}. The official tallest red alder (as of 1979) stands {{convert|32|m|ft|abbr=on}} tall in [[Clatsop County, Oregon]] (US).<ref name="Furlow-1979" /> The trunks range from {{Convert|25 to 50|cm|frac=2}} in diameter.<ref name="Arno-2020">{{Cite book |last1=Arno |first1=Stephen F. |url=https://books.google.com/books?id=qDD4DwAAQBAJ |title=Northwest Trees: Identifying & Understanding the Region's Native Trees |last2=Hammerly |first2=Ramona P. |publisher=[[Mountaineers Books]] |year=2020 |isbn=978-1-68051-329-5 |edition=field guide |location=Seattle |pages=208–215 |language=en |oclc=1141235469 |orig-date=1977}}</ref> The bark is mottled, ashy-gray and smooth, often colonized by white [[lichen]] and [[moss]].<ref name="Arno-2020" /> The [[leaves]] are [[Glossary of botanical terms|ovate]], {{convert|7|to|15|cm|frac=4|in}} long, with bluntly serrated edges and a distinct point at the end; the leaf margin is revolute, the very edge being curled under, a diagnostic character which distinguishes it from all other alders. Rather than turning yellow in autumn, its leaves darken in colour and wither before they are shed. The male [[flower]]s are dangling reddish [[catkin]]s {{convert|10|to|15|cm|in|abbr=on|frac=4}} long in early spring. Female flowers occur in clusters of (3) 4–6 (8). Female catkins are erect during anthesis, but otherwise pendant. They develop into small, woody, superficially [[conifer cone|cone]]-like oval dry [[fruit]] {{convert|2|to|3|cm|in|abbr=on|frac=4}} long. The [[seed]]s develop between the woody bracts of the 'cones' and are shed in late autumn and winter. Red alder seeds have a membranous winged margin that allows long-distance dispersal.<ref name="Furlow-1979">Furlow, J. (1979). The systematics of the American species of Alnus. Rhodora, v81-825: 1-248.</ref>

Specimens can live to about 60 years of age before being seriously afflicted by [[heart rot]].<ref name="Arno-2020" />

==Taxonomy==
The name derives from the bright rusty red color that develops in bruised or scraped bark.<ref name="Furlow-1979" />

==Distribution==
''Alnus rubra'' grows from [[Southeast Alaska]] to central coastal [[California]], nearly always within about {{convert|200|km|mi}} of the [[Pacific]] coast, except for an extension {{convert|600|km|abbr=on}} inland across [[Washington (state)|Washington]] and [[Oregon]] into northernmost [[Montana]].<ref name=bonap/>{{r|fna}} It can be found from sea level to elevations of {{Convert|900|m|abbr=on}}.<ref name="Arno-2020" />

==Ecology==
In southern Alaska, western [[British Columbia]] and the northwestern [[Pacific Coast Ranges]] of the United States, red alder grows on cool and moist slopes; inland and at the southern end of its range (California) it grows mostly along the margins of watercourses and wetlands.{{r|jepson}} It is [[Shade tolerance|shade intolerant]].<ref name="Arno-2020" />

In moist forest areas, ''Alnus rubra'' will [[Pioneer species|rapidly cover]] a former burn or [[clearcutting|clearcut]], often preventing the establishment of [[conifer]]s. It is a prolific seed producer,<ref name="Arno-2020" /> but the small, wind-dispersed seeds require an open area of mineral [[soil]] to [[Germination|germinate]], and so skid trails and other areas disturbed by logging or fire are ideal seedbeds. Such areas may host several hundred thousand to several million seedlings per hectare in the first year after landscape disturbance.{{r|zavit1972}}

Twigs and buds of alder are only fair browse for wildlife, but [[deer]] and [[red deer|elk]] browse the twigs in fall and twigs and buds in the winter and spring. [[Beaver]] occasionally eat the bark, though it is not a preferred species. Several [[finch]]es eat alder seeds, notably [[common redpoll]] and [[pine siskin]], and as do [[deer mouse|deer mice]]. [[Tent caterpillar]]s often feed on the leaves, but the trees usually recover within a year.<ref name="Arno-2020" />

The tree hosts the [[nitrogen-fixing]] actinomycete ''[[Frankia]]'' in nodules on roots. This association allows alder to grow in nitrogen-poor soils, and makes the species an important early colonizer of disturbed forests and riparian areas. This self-fertilizing trait allows red alder to grow rapidly, and makes it effective in covering disturbed and/or degraded land, such as [[Mining|mine]] spoils. Imported Red Alder has been found to be able to make successful associations with Frankia strains present in the UK.<ref>{{Cite journal |last1=Malcolm |first1=D. C. |last2=Hooker |first2=J. E. |last3=Wheeler |first3=C. T. |date=January 1985 |title=Frankia symbiosis as a source of nitrogen in forestry: a case study of symbiotic nitrogen-fixation in a mixed Alnus-Picea plantation in Scotland |url=https://www.cambridge.org/core/journals/proceedings-of-the-royal-society-of-edinburgh-section-b-biological-sciences/article/abs/frankia-symbiosis-as-a-source-of-nitrogen-in-forestry-a-case-study-of-symbiotic-nitrogenfixation-in-a-mixed-alnuspicea-plantation-in-scotland/2C74DEDBDD1D589D8400F549F6B9E141 |journal=Proceedings of the Royal Society of Edinburgh, Section B: Biological Sciences |language=en |volume=85 |issue=3–4 |pages=263–282 |doi=10.1017/S0269727000004061 |issn=2053-5910|url-access=subscription }}</ref> Alder leaves, shed in the fall, decay readily to form a nitrogen-enriched [[humus]] making the nitrogen available to other species.

===Common associates===
Red alder is associated with [[coast Douglas-fir]] (''Pseudotsuga menziesii'' subsp. ''menziesii''), [[western hemlock]] (''Tsuga heterophylla''), [[Abies grandis|grand fir]] (''Abies grandis''), [[Thuja plicata|western redcedar]] (''Thuja plicata''), and [[Sitka spruce]] (''Picea sitchensis'') forests.

Along stream banks, it is commonly associated with [[willow]]s (''Salix'' spp.), [[red osier dogwood]] (''Cornus stolonifera''), [[Oregon ash]] (''Fraxinus latifolia''), and [[bigleaf maple]] (''Acer macrophyllum'').

To the southeast of its range it is replaced by [[Alnus rhombifolia|white alder]] (''Alnus rhombifolia''), which is a tree of similar stature, but which differs in the leaf margins not being rolled under, lack of distinct lobes, and lack of membranous wings on seed margins. In the high mountains it is replaced by the smaller and more shrub-like [[Sitka alder]] (''Alnus viridis'' subsp. ''sinuata''), and east of the [[Cascade Mountains]] by [[Grey Alder|thinleaf alder]] (''Alnus incana'' subsp. ''tenuifolia'').

==Uses==
[[Image:Alnus rubra 28199.JPG|right|thumb|Broken branch showing red weathered bark]]
[[Image:Alder showing ozone discolouration.jpg|thumb|right|Typical leaf discoloration caused by [[ozone]] pollution]]

===As dye===
A russet dye can be made from a decoction of the bark, apparently due to the [[tannin]] it contains,<ref name="Arno-2020" /> and was used by [[Indigenous peoples of the Americas|Native Americans]] to dye fishing nets so as to make them less visible underwater.<ref name="Arno-2020" />

===Medicine===
Native Americans used red alder bark to treat [[poison oak reactions]], insect bites, and skin irritations. Blackfeet Indians used an infusion made from the bark of red alder to treat lymphatic disorders and tuberculosis. Recent clinical studies have verified that red alder contains [[betulin]] and [[lupeol]], compounds shown to be effective against a variety of [[tumor]]s.<ref>{{cite book |title=Edible and Medicinal Plants of the West |first=Gregory L. |last=Tilford |isbn=0-87842-359-1 |publisher=Mountain Press |edition=1st  |date=15 June 1997}}</ref>

===Restoration===
In addition to its use as a nitrogen fixer, red alder is occasionally used as a [[crop rotation|rotation crop]] to discourage the conifer root pathogen ''[[Phellinus weirii]]'' (causing [[laminated root rot]]).

''Alnus rubra'' are occasionally planted as [[ornamental tree]]s and will do well in [[Swale (landform)|Swale]]s, [[riparian]] areas, or on stream banks, in light-textured soils that drain well. Red alder does not thrive in heavy, wet clay soils. If planted domestically, alders should be planted well away from drainpipes, [[sewage]] pipes, and water lines, as the roots may invade and clog the lines.{{Citation needed|date=March 2009}}

===Woodworking===
Alder lumber is not considered to be a durable option for outdoor applications,{{Who|date=April 2010}} but due to its workability and ease of finishing it is increasingly used for furniture and cabinetry. Because it is softer than other popular hardwoods such as [[maple]], [[walnut]] and [[fraxinus|ash]], alder has historically been considered of low value for [[timber]]. However it is now becoming one of the more popular hardwood alternatives as it is economically priced compared to other hardwoods. In the world of musical instrument construction, red alder is valued by some electric guitar / electric bass builders for its balanced tonality. Alder is frequently used by Native Americans for making masks, bowls, tool handles, and other small goods.

The appearance of alder lumber ranges from white through pinkish to light brown, has a relatively soft texture, minimal grain, and has medium luster. It is easily worked, glues well, and takes a good finish.

===Fish smoking===
Because of its oily smoke, ''A. rubra is a'' is the wood of choice for smoking salmon.<ref>{{cite book |last=Ewing |first=Susan |title=The Great Alaska Nature Factbook |place=Portland, OR |publisher=Alaska Northwest Books |year=1996}}</ref>

===As an environmental indicator===
Red alder is often used by scientists as a [[biomonitoring]] organism to locate areas prone to [[ozone]] pollution, as the leaves react to the presence of high ozone levels by developing red to brown or purple discolorations.<ref name=EONASA>{{cite web|url=http://earthobservatory.nasa.gov/Library/OzoneWx/|access-date=2008-10-11|title=Watching Our Ozone Weather|date=2003-08-22|author=Jeannie Allen|publisher=NASA Earth Observatory| archive-url=https://web.archive.org/web/20081020145630/http://earthobservatory.nasa.gov/Library/OzoneWx/| archive-date=2008-10-20 | url-status=live}}</ref>

=== Forestry ===
[[Image:RedAlder 7504.jpg|thumb|Red alder, western hemlock, and bigleaf maple forest]]
With a current inventory of about {{ Convert | 7.4 | e9cuft | abbr=off }}, red alder comprises 60% of the total hardwood volume in the Pacific Northwest, and is by far the most valuable hardwood in term of diversity of products, commercial value, and manufacturing employment.<ref>{{cite book |author1=Hibbs, D.E. |author2=DeBell, D.S. |author3=Tarrant, R.F. |year=1995 |title=The Biology and Management of Red Alder |place=Corvallis, OR |publisher=Oregon State University Press}}</ref> Increasing value of alder logs, combined with a better understanding of the species' ecological role, has led some land managers to tolerate and, in some cases, manage for alder.

As an "aggressive pioneer" that was freely able to rapidly colonise areas to the detriment of the more valuable conifer species, it was regarded for a long time as a weed<ref>{{Cite journal |last1=Burns |first1=Russell M. |last2=Honkala |first2=Barbara H. |last3=Coordinators |first3=Technical |date=1990 |title=Silvics of North America: Volume 2. Hardwoods |url=https://research.fs.usda.gov/treesearch/1548 |journal=United States Department of Agriculture (USDA), Forest Service, Agriculture Handbook 654 |language=en}}</ref> and was neglected for its timber potential, however breeding programmes to improve stem form and timber quality<ref>{{Cite journal |last=Xie |first=C. Y. |date=2008 |title=Ten-year results from red alder ( Alnus rubra Bong.) provenance-progeny testing and their implications for genetic improvement |url=https://www.researchgate.net/publication/227330113 |journal=New Forests |volume=36 |issue=3 |pages=273–284|doi=10.1007/s11056-008-9098-3 }}</ref> are now underway.

Since most forest land in the Northwest is managed for conifer production, over {{Convert|80,000|ha|abbr=off|order=flip}} of timberland are sprayed with [[herbicide]]s annually in Oregon alone to control red alder and other competing hardwood species.<ref>Oregon Dept of Forestry 2014{{full citation needed|date=July 2020}}</ref> Red alder's rapid early growth can interfere with establishment of conifer plantations.<ref>{{cite journal |last=Haeussler |first=S.T.J. |year=1995 |title=Germination, survival and early growth of red alder seedlings in the central Coast Range of Oregon |journal=Canadian Journal of Forest Research |volume=25 |issue=10 |pages=1639–1651|doi=10.1139/x95-178 }}</ref> Herbicide spraying of red alder over large areas of coastal Oregon and Washington has resulted in a number of lawsuits claiming it has caused health problems, including [[birth defect]]s and other human health effects.<ref>{{cite news |last=Lobet |first=Ingrid |date=14 August 2012 |title=In Oregon, Residents Struggle to Solve a Pesticide Mystery |url=https://www.theatlantic.com/national/archive/2012/08/in-oregon-residents-struggle-to-solve-a-pesticide-mystery/261083/ |access-date=2 February 2021 |work=The Atlantic}}</ref><ref>{{cite web|url=https://andrewsforest.oregonstate.edu/sites/default/files/lter/pubs/pdf/pub820.pdf|title=Basal Spraying of Red Alder|access-date=2 February 2021}}</ref>

In addition to adding soil nitrogen, rotations of red alder are used to reduce laminated root rot in Douglas-fir forests. Nurse stands of red alder may also reduce spruce weevil damage in Sitka spruce stands on the Olympic Peninsula.<ref>{{cite tech report |chapter-url=https://www.for.gov.bc.ca/hfd/library/FIA/2007/FSP_Y073159b.pdf |first=Lyle |last=Almond |chapter=The value of red alder as an integrated pest management tool for controlling weevil damage to sitka spruce |title=Red Alder: A State of Knowledge |editor1=Deal, R.L. |editor2=Harrington, C.A. |date=2006 |id=General Technical Report PNW-GTR-669 |publisher=U.S. Department of Agriculture |department=Pacific Northwest Research Station |location=Portland, OR |via=Department of Forestry, Province of British Columbia, Canada}}</ref> Alder continues to attract interest as log values approach and often exceed those of Douglas-fir.<ref>{{cite report |url=http://extension.oregonstate.edu/clackamas/sites/default/files/9d-bluhm-redaldermgtrev.pdf |title=Red alder management: Silviculture to marketing |orig-date=31 July 2010 |series=Tree School |place=Oregon City, OR |date=25 March 2017 |access-date=2017-12-07 |first=Andrew A. |last=Bluhm |archive-url=https://web.archive.org/web/20171207191852/http://extension.oregonstate.edu/clackamas/sites/default/files/9d-bluhm-redaldermgtrev.pdf |archive-date=2017-12-07 |via=Oregon State University Agricultural Extension Service}}</ref> This interest is limited by red alder's total stand productivity, which is significantly lower than that of Douglas-fir and western hemlock.

==Gallery==
<gallery>
Alnus rubra 9819.JPG|Male catkins with tiny female catkins above
Alnus rubra 9853.JPG|Stump
Alnus rubra seeds.jpg|Seeds
Kitlope rainforest.jpg|Habitat in British Columbia
Alder_Bass_Body_Blank_paint.jpg| In luthiery
</gallery>

==References==
{{Reflist|25em|refs=

<ref name=fna>{{cite web |series=Flora of North America |url=http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500039 |title=''Alnus rubra'' |website=efloras.org}}</ref>

<ref name=jepson>{{cite web |series=Jepson Flora |url=http://ucjeps.berkeley.edu/cgi-bin/get_JM_treatment.pl?Alnus+rubra |title=''Alnus rubra'' |publisher=University of California |place=Berkeley, CA}}</ref>

<ref name=ubc>{{cite web |series=Plants of British Columbia |url=http://linnet.geog.ubc.ca/Atlas/Atlas.aspx?sciname=Alnus+rubra |title=''Alnus rubra'' |publisher=University of British Columbia |place=Vancouver, BC |access-date=2007-11-25 |archive-date=2008-02-11 |archive-url=https://web.archive.org/web/20080211195039/http://linnet.geog.ubc.ca/Atlas/Atlas.aspx?sciname=Alnus+rubra }}</ref>

<ref name=zavit1972>{{cite journal |doi=10.2307/1934076 |last1=Zavitkovski |first1=J. |last2=Stevens |first2=R.D. |year=1972 |title=Primary productivity of red alder ecosystems |journal=Ecology |volume=53 |issue=2 |pages=235–242 |jstor=1934076|bibcode=1972Ecol...53..235Z }}</ref>

}}

==External links==
{{Commons category}}
* {{PFAF|Alnus rubra}}
* {{CalPhotos|Alnus|rubra}}

{{Taxonbar|from=Q1818806}}
{{Authority control}}

[[Category:Alnus|rubra]]
[[Category:Plants described in 1833]]
[[Category:Plant dyes]]
[[Category:Trees of Northern America]]
[[Category:Flora of Oregon]]