Fraxinus pennsylvanica

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Fraxinus pennsylvanica
Fraxinus pensylvanica a1.jpg
Leaves and fruit
Status TNC G4.svg
Apparently Secure  (NatureServe) [2]
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Lamiales
Family: Oleaceae
Genus: Fraxinus
Section: Fraxinus sect. Melioides
Species:
F. pennsylvanica
Binomial name
Fraxinus pennsylvanica
Fraxinus pennsylvanica range map 3.png
Natural range of Fraxinus pennsylvanica

Fraxinus pennsylvanica, the green ash or red ash, [3] is a species of ash native to eastern and central North America, from Nova Scotia west to southeastern Alberta and eastern Colorado, south to northern Florida, and southwest to Oklahoma and eastern Texas. It has spread and become naturalized in much of the western United States and also in Europe from Spain to Russia. [4] [5] [6]

Contents

Other names more rarely used include downy ash, swamp ash, and water ash.

Description

Bark Green Ash Fraxinus pennsylvanica Bark 2000px.jpg
Bark

Fraxinus pennsylvanica is a medium-sized deciduous tree reaching 12–25 metres (39–82 feet) (rarely to 45 m or 148 ft) tall with a trunk up to 60 centimetres (24 inches) in diameter. The bark is smooth and gray on young trees, becoming thick and fissured with age. The winter buds are reddish-brown, with a velvety texture. The leaves are 15–30 cm (6–12 in) long, oppositely arranged, pinnately compound with seven to nine (occasionally five or eleven) leaflets, these 5–15 cm (2–6 in) (rarely 18 cm or 7 in) long and 1.2–9 cm (1⁄2–3+9⁄16 in) broad, with serrated margins and short but distinct, downy petiolules a few millimeters long. They are green both above and below. The autumn color is golden-yellow and depending on the climate, green ash's leaves may begin changing color the first week of September.[ where? ] The flowers are produced in spring at the same time as the new leaves, in compact panicles; they are inconspicuous with no petals, and are wind-pollinated. The fruit is a samara 2.5–7.5 cm (1–3 in) long comprising a single seed 1.5–3 cm (5⁄8–1+1⁄8 in) long with an elongated apical wing 2–4 cm (3⁄4–1+1⁄2 in) long and 3–7 mm (1⁄8–9⁄32 in) broad. [7] [8] [9] [10]

It is sometimes divided into two varieties, Fraxinus pennsylvanica var. pennsylvanica (red ash) and Fraxinus pennsylvanica var. lanceolata (Borkh.) Sarg. (syn. var. subintegerrima (Vahl) Fern.; green ash) on the basis of the hairless leaves with narrower leaflets of the latter, but the two intergrade completely, and the distinction is no longer upheld by most botanists. [4]

Like other species in the section Melioides, Fraxinus pennsylvanica is dioecious, with male and female flowers produced on separate individuals. [11]

Ecology

Bark and leaf Fraxinus pennsylvanica.jpg
Bark and leaf

It is the most widely distributed of all the American ashes; its range centers on the midwestern U.S. and Great Plains. Seedlings of the tree have a high tolerance to water logging [12] which may explain why the natural habitat of green ash is almost exclusively stream sides and bottomlands. The large seed crops provide food to many kinds of wildlife. [3]

Green ash is threatened by the emerald ash borer, a beetle introduced from Asia. This introduced pest kills most ash trees that it infests, accounting for mass die-offs of ashes in North America and in Moscow, Russia. [13] Asian ashes have a high tannin content in their leaves which makes them unpalatable to the beetle, while most American species (with the notable exception of blue ash) do not. [14] A common garden experiment showed that green ash is killed readily when exposed to emerald ash borer, while the Asian species F. mandschurica shows resistance against emerald ash borer. [15]

The United States Forest Service has discovered small numbers of "lingering ash" trees in the wild that have remained healthy after emerald ash borer swept through the population. [16] The possibility of these trees possessing genetic resistance to the beetle is currently being investigated with the hope that green ash could be restored using the surviving trees. [17] Although larval infestation by the invasive emerald ash borer kills more 99% of green ash trees, it has been found that emerald ash borer infestation induces production of secoiridoids in infested trees and that cultivars that are progeny of "lingering ash" produce higher levels of these secoiridoids than progeny of susceptible trees. [18]

Winter twig of Fraxinus pennsylvanica. Green ash can usually be distinguished from white ash (F. americana) by its D-shaped leaf scars. In F. americana, the lateral buds are more deeply recessed within their corresponding leaf scars, giving the latter a more C-shaped appearance. Pensilvanski iasen - klonka.jpg
Winter twig of Fraxinus pennsylvanica. Green ash can usually be distinguished from white ash (F. americana) by its D-shaped leaf scars. In F. americana, the lateral buds are more deeply recessed within their corresponding leaf scars, giving the latter a more C-shaped appearance.

The spread of emerald ash borer was facilitated by the extensive use of green ash as an ornamental tree in the central U.S. following the loss of American elms in the 1950s–60s due to Dutch elm disease. That epidemic was the result of a similar overuse of elms in urban environments, leading to a monoculture that lacked any disease or pest resistance. Scientifically for green ash this is because modern cultivars utilized regionally were parented from sometimes only four individual trees selected for unique traits and male seedless flowering. Proclaiming a harsh lesson learned, cities like Chicago did not replace dead elms with a 1:1 ash:elm ratio. Instead, Norway, silver, red and sugar maples, honey locust, linden/basswood, redbud, crabapples, and hackberry, among others, were also utilized during this recovery period and in new urban and suburban areas. Fortunately, with these additional species, many cities were able to reduce the percent of ash and other species to much lower levels (20% average) than during the Dutch elm disease era where from 56% to 100% of the trees were elm.

Injections and spraying of ashes with pesticides has been used in city parks to protect valued trees from emerald ash borer. [20]

Record cold temperatures during the winter of 2018–19 are estimated to have killed as much as 80% of ash borer larvae in the Upper Midwest. [21]

Both American elm and green ash were extremely popular due to rapid growth and tolerance of urban pollution and road salt, so many housing developments in Michigan were lined from end to end with ashes, a result of which the beetles had an enormous food supply to boost their population well above Infestation thresholds. The tree was also extensively propagated and sold by local nurseries. According to the American Nursery Industry, "Back in the late 1980s, Dr. Frank Santamour Jr., then a research geneticist with the U.S. National Arboretum, proposed the 10-20-30 formula for diversity in the urban forest, limiting the plantings in a community to no more than 10 percent within a single species, 20 percent within a genus and 30 percent within a family." Many communities are using a more strict 5-10-20 rule today, because of the threat posed by emerald ash borer.

The emerald ash borer proved to be a far worse and potentially more serious threat than epidemics of the past such as chestnut blight and Dutch elm disease because those diseases spread at a slower rate, only affected one species, and did not kill the trees before they could attain reproductive maturity. Many areas have banned the sale of ash seedlings in nurseries, although seeds may be sold as they are not a vector for the insect.

Green ash is also vulnerable to many other diseases including ash yellows, ash dieback and ash bacterial canker that can cause gradual loss of vigor and exhibit similar symptoms to emerald ash borer infestation such as crown dieback, bark cracking, and epicormal sprouts. These conditions are most common on stressed trees in areas of poor soil, urban pollution, and lack of moisture. A wave of ash dieback struck the northeastern United States in the 1950s–60s that killed an estimated 70% of ashes in the region.

Uses

Urban ornamental trees

Autumn leaf color 2014-10-29 13 12 58 Green Ash foliage during autumn coloration in Ewing, New Jersey.JPG
Autumn leaf color

Green ash is one of the most widely planted ornamental trees throughout the United States and much of Canada but mostly Alberta, including in western areas where it is not native. It is also widely planted in Argentina. It is very popular due to its good form and resistance to disease. About 40% of boulevard trees in Edmonton, Alberta, are green ash. [22] It is often planted for shade or as a windbreak. [23]

For the last two centuries American elm and ash, which both belong to the ancient Elm-Ash-Cottonwood Bottomland ecosystem, [24] achieved distinction as North America's two most popularly planted urban species, used primarily for their superior survival traits and slowly maturing 180–300 year majestic natural beauty. Today used as living national monuments, the National Park Service is protecting Thomas Jefferson's 200-year-old planted example, and George Washington's 250-year-old white ash which has a 600-year possible lifespan.[ citation needed ] Green ash had been widely used as a primary ornamental and long lived monument tree until the elm fad of the 1880s, and regained top position once again after Dutch elm disease arrived.[ citation needed ]

Other continents learned of American ash species' urban survivability and unique beauty through the worldwide popularity of Midwestern Prairie style ecology and architectural movement. Modernizing cities in Russia and China then began using imported green ash a century ago to line streets and landscape new public parks. [25] [26] Advantages of green ash include its tolerance of harsh urban environmental conditions, ease of propagation, and (in eastern North America) its value for wildlife as a native keystone species. [27]

Utility to wildlife

North American native ash tree species are used by North American frogs as a critical food source, as the leaves that fall from the trees are particularly suitable for tadpoles to feed upon in ponds (both temporary and permanent), large puddles, and other water sources. [28] Species such as red maple, which are taking the place of ash due to the ash borer, are much less suitable for the frogs as a food source — resulting in poor frog survival rates and small frog sizes. [28] It is the lack of tannins in the American ash varieties that makes them good for the frogs as a food source and also not resistant to the ash borer. Varieties of ash from outside North America typically have much higher tannin levels and resist the borer. Maples and various non-native invasive trees, trees that are taking the place of American ash species in the North American ecosystem, typically have much higher leaf tannin levels. [28]

Other uses

Green ash wood is similar in properties to white ash wood, and is marketed together as "white ash". The commercial supply is mostly in the South. It is very popular, used in making electric guitars because it can be somewhat lighter than white ash without sacrificing too much in tone.[ dubious – discuss ] It has a bright sound with long sustain, plus the wood grain is aesthetically desirable to many guitar players.[ dubious – discuss ] Gibson, Fender, Ibanez, Warwick, and many other luthiers use ash in the construction of their guitars.

Related Research Articles

<i>Fraxinus</i> Genus of plants

Fraxinus, commonly called ash, is a genus of plants in the olive and lilac family, Oleaceae, and comprises 45–65 species of usually medium-to-large trees, most of which are deciduous trees, although some subtropical species are evergreen trees. The genus is widespread throughout much of Europe, Asia, and North America.

<i>Fraxinus quadrangulata</i> Species of ash

Fraxinus quadrangulata, the blue ash, is a species of ash native primarily to the Midwestern United States from Oklahoma to Michigan, as well as the Bluegrass region of Kentucky and the Nashville Basin region of Tennessee. Isolated populations exist in Alabama, Southern Ontario, and small sections of the Appalachian Mountains. It is typically found over calcareous substrates such as limestone, growing on limestone slopes and in moist valley soils, at elevations of 120–600 m.

<i>Fraxinus americana</i> Species of ash

Fraxinus americana, the white ash or American ash, is a fast-growing species of ash tree native to eastern and central North America.

<i>Fraxinus excelsior</i> Species of deciduous tree in the family Oleaceae

Fraxinus excelsior, known as the ash, or European ash or common ash to distinguish it from other types of ash, is a flowering plant species in the olive family Oleaceae. It is native throughout mainland Europe east to the Caucasus and Alborz mountains, and Great Britain and Ireland, the latter determining its western boundary. The northernmost location is in the Trondheimsfjord region of Norway. The species is widely cultivated and reportedly naturalised in New Zealand and in scattered locales in the United States and Canada.

<span class="mw-page-title-main">Emerald ash borer</span> Species of beetle

The emerald ash borer, also known by the acronym EAB, is a green buprestid or jewel beetle native to north-eastern Asia that feeds on ash species. Females lay eggs in bark crevices on ash trees, and larvae feed underneath the bark of ash trees to emerge as adults in one to two years. In its native range, it is typically found at low densities and does not cause significant damage to trees native to the area. Outside its native range, it is an invasive species and is highly destructive to ash trees native to Europe and North America. Before it was found in North America, very little was known about emerald ash borer in its native range; this has resulted in much of the research on its biology being focused in North America. Local governments in North America are attempting to control it by monitoring its spread, diversifying tree species, and through the use of insecticides and biological control.

<i>Fraxinus nigra</i> Species of ash

Fraxinus nigra, the black ash, is a species of ash native to much of eastern Canada and the northeastern United States, from western Newfoundland west to southeastern Manitoba, and south to Illinois and northern Virginia. Formerly abundant, as of 2017 the species is threatened with near total extirpation throughout its range within the next century as a result of infestation by an invasive parasitic insect known as the emerald ash borer.

<i>Chionanthus virginicus</i> Species of tree

Chionanthus virginicus is a tree native to the savannas and lowlands of the northeastern and southeastern United States, from Massachusetts south to Florida, and west to Oklahoma and Texas.

<i>Fraxinus mandschurica</i> Species of ash

Fraxinus mandshurica, the Manchurian ash, is a species of Fraxinus native to northeastern Asia in northern China, Korea, Japan and southeastern Russia.

<i>Carya aquatica</i> Species of tree

Carya aquatica, the bitter pecan or water hickory, is a large tree, that can grow over 30 metres (98 ft) tall of the Juglandaceae or walnut family. In the American South it is a dominant plant species found on clay flats and backwater areas near streams and rivers. The species reproduces aggressively both by seed and sprouts from roots and from stumps of cut trees. Water hickory is a major component of wetland forests now in the south eastern US, because of the selective cutting of more desirable tree species for the lumber industry. It is considered important in cleansing drainage waters since the plants slow water flow during flooding, allowing sediments to fall out of the water column. This tree species is tolerant of wet soils but grows best on well draining soils near rivers and other water ways.

<i>Fraxinus profunda</i> Species of ash

Fraxinus profunda, the pumpkin ash, is a species of ash (Fraxinus) native to eastern North America, where it has a scattered distribution on the Atlantic coastal plain and interior lowland river valleys from the Lake Erie basin in Ontario and New York west to Illinois, southwest to Missouri and southeast to northern Florida. It grows in bottomland habitats, such as swamps, floodplains and riverbanks. It is threatened by the emerald ash borer, an invasive insect which has caused widespread destruction of ash trees in eastern North America.

<i>Fraxinus caroliniana</i> Species of ash

Fraxinus caroliniana, the pop ash, Florida ash, swamp ash, Carolina ash, or water ash, is a species of ash tree native from Cuba through the subtropical Southeastern United States from southern Virginia to Texas. It was originally described by the botanist Philip Miller. It is a small tree about 40 ft. Leaves are compound, opposite, 7–12 in long, leaflets 5–7 in, ovate to oblong, coarsely serrate or entire, 3–6 in long, 2–3 in wide. Fruit is frequently 3-winged (samara) with flat seed portion; seed sometimes a bright violet color. It is the smallest of eastern North American ash species, wood light, soft, weak, 22 lbs./cu.ft. Typical to coastal swamps and subtropical lowlands. Like other species in the section Melioides, Fraxinus caroliniana is dioecious, with male and female flowers produced on separate individuals.

<i>Tetrastichus planipennisi</i> Species of wasp

Tetrastichus planipennisi is a parasitic non-stinging wasp of the family Eulophidae which is native to North Asia. It is a parasitoid of the emerald ash borer, an invasive species which has destroyed tens of millions of ash trees in its introduced range in North America. As part of the campaign against the emerald ash borer (EAB), American scientists in conjunction with the Chinese Academy of Forestry searched since 2003 for its natural enemies in the wild leading to the discovery of several parasitoid wasps, including Tetrastichus planipennisi which is a gregarious endoparasitoid of EAB larvae on Manchurian Ash and has been recorded to attack and kill up to 50 percent of EAB larvae.

<i>Oobius agrili</i> Species of wasp

Oobius agrili is a parasitic non-stinging wasp of family Encyrtidae which is native to North Asia. It is a parasitoid of the emerald ash borer, an invasive species which has destroyed tens of millions of ash trees in its introduced range in North America. As part of the campaign against the emerald ash borer (EAB), American scientists in conjunction with the Chinese Academy of Forestry searched since 2003 for its natural enemies in the wild leading to the discovery of several parasitoid wasps, including Oobius agrili, which is a solitary egg parasitoid of EAB found on ash trees in Jilin province in 2004; it has been recorded to kill up to 60 percent of EAB eggs.

<i>Spathius agrili</i> Species of wasp

Spathius agrili is a parasitic non-stinging wasp of family Braconidae which is native to North Asia. It is a parasitoid of the emerald ash borer, an invasive species which has destroyed tens of millions of ash trees in its introduced range in North America. As part of the campaign against the emerald ash borer (EAB), American scientists in conjunction with the Chinese Academy of Forestry began searching in 2003 for its natural enemies in the wild, leading to the discovery of several parasitoid wasp species, including Spathius agrili. S. agrili was discovered in Tianjin, China where it is a prevalent parasitoid of EAB larvae in stands of an introduced ash species, and an endemic ash species. S. agrili has been recorded to attack and kill up to 90 percent of EAB larvae.

<i>Hymenoscyphus fraxineus</i> Fungus, cause of ash dieback

Hymenoscyphus fraxineus is an ascomycete fungus that causes ash dieback, a chronic fungal disease of ash trees in Europe characterised by leaf loss and crown dieback in infected trees. The fungus was first scientifically described in 2006 under the name Chalara fraxinea. Four years later it was discovered that Chalara fraxinea is the asexual (anamorphic) stage of a fungus that was subsequently named Hymenoscyphus pseudoalbidus and then renamed as Hymenoscyphus fraxineus.

<span class="mw-page-title-main">Forestry in Canada</span>

The Canadian forestry industry is a major contributor to the Canadian economy. With 39% of Canada's land acreage covered by forests, the country contains 9% of the world's forested land. The forests are made up primarily of spruce, poplar and pine. The Canadian forestry industry is composed of three main sectors: solid wood manufacturing, pulp and paper and logging. Forests, as well as forestry are managed by The Department of Natural Resources Canada and the Canadian Forest Service, in cooperation with several organizations which represent government groups, officials, policy experts, and numerous other stakeholders. Extensive deforestation by European settlers during the 18th and 19th centuries has been halted by more modern policies. Today, less than 1% of Canada's forests are affected by logging each year. Canada is the 2nd largest exporter of wood products, and produces 12.3% of the global market share. Economic concerns related to forestry include greenhouse gas emissions, biotechnology, biological diversity, and infestation by pests such as the mountain pine beetle.

<i>Candidatus</i> Phytoplasma fraxini Species of bacterium

CandidatusPhytoplasma fraxini is a species of phytoplasma, a specialized group of bacteria which lack a cell wall and attack the phloem of plants. This phytoplasma causes the diseases ash yellows and lilac witches' broom.

<i>Spathius galinae</i> Species of wasp

Spathius galinae is a parasitoid of emerald ash borer. The known range of S. galinae extends from the Russian Far East to South Korea. It is currently approved for release in some areas of North America as part of a biological control program against emerald ash borer.

<span class="mw-page-title-main">Forest disturbance by invasive insects and diseases in the United States</span>

Species which are not native to a forest ecosystem can act as an agent of disturbance, changing forest dynamics as they invade and spread. Invasive insects and pathogens (diseases) are introduced to the United States through international trade, and spread through means of natural and human-dispersal. Invasive insects and pathogens are a serious threat to many forests in the United States and have decimated populations of several tree species, including American chestnut, American elm, eastern hemlock, whitebark pine, and the native ash species. The loss of these tree species is typically rapid with both short and long-term impacts to the forest ecosystem.

<i>Fraxinus platypoda</i> Species of plant in the family Oleaceae

Fraxinus platypoda, the Chinese red ash, is a species of flowering plant in the family Oleaceae, native to central China, and Japan. In the latter stages of succession it often dominates the mountain riparian forest habitat in which it is found.

References

  1. ↑ Westwood, M.; Oldfield, S.; Jerome, D.; Romero-Severson, J. (2017). "Fraxinus pennsylvanica". IUCN Red List of Threatened Species . 2017: e.T61918934A61919002. doi: 10.2305/IUCN.UK.2017-2.RLTS.T61918934A61919002.en . Retrieved 12 November 2021.
  2. ↑ NatureServe (2 February 2024). "Fraxinus pennsylvanica". NatureServe Network Biodiversity Location Data accessed through NatureServe Explorer. Arlington, Virginia: NatureServe. Retrieved 7 February 2024.
  3. 1 2 Kennedy Jr., Harvey E. (1990). "Fraxinus pennsylvanica". In Burns, Russell M.; Honkala, Barbara H. (eds.). Hardwoods. Silvics of North America. Vol. 2. Washington, D.C.: United States Forest Service (USFS), United States Department of Agriculture (USDA) – via Southern Research Station.
  4. 1 2 "Fraxinus pennsylvanica". Germplasm Resources Information Network . Agricultural Research Service, United States Department of Agriculture.
  5. ↑ "Fraxinus pennsylvanica". World Checklist of Selected Plant Families (WCSP). Royal Botanic Gardens, Kew.
  6. ↑ "Fraxinus pennsylvanica". County-level distribution map from the North American Plant Atlas (NAPA). Biota of North America Program (BONAP). 2014.
  7. ↑ Common Trees of the North Carolina Piedmont: Fraxinus pennsylvanica
  8. ↑ Northern Ontario Plant Database: Fraxinus pennsylvanica
  9. ↑ Virtual Herbarium of the Chicago Region: Fraxinus pennsylvanica Archived 2007-08-13 at the Wayback Machine
  10. ↑ Oklahoma Biological Survey: Fraxinus pennsylvanica
  11. ↑ Wallander, Eva (2008). "Systematics of Fraxinus (Oleaceae) and evolution of dioecy". Plant Systematics and Evolution. 273 (1–2): 25–49. Bibcode:2008PSyEv.273...25W. doi:10.1007/s00606-008-0005-3. S2CID   24152294.
  12. ↑ Levinsson, Anna; Emilsson, Tobias; Sjöman, Henrik; Wiström, Björn (January 2024). "Using stomatal conductance capacity during water stress as a tool for tree species selection for urban stormwater control systems". Urban Forestry & Urban Greening. 91: 128164. doi:10.1016/j.ufug.2023.128164.
  13. ↑ Sun, Jianghua; Koski, Tuuli-Marjaana; Wickham, Jacob D.; Baranchikov, Yuri N.; Bushley, Kathryn E. (7 January 2024). "Emerald Ash Borer Management and Research: Decades of Damage and Still Expanding". Annual Review of Entomology. 69 (1). doi:10.1146/annurev-ento-012323-032231.
  14. ↑ Emerald ash borer: EAB website
  15. ↑ Rebek, Eric J.; Herms, Daniel A.; Smitley, David R. (1 February 2008). "Interspecific Variation in Resistance to Emerald Ash Borer (Coleoptera: Buprestidae) Among North American and Asian Ash (Fraxinus spp.)". Environmental Entomology. 37 (1): 242–246. doi: 10.1603/0046-225X(2008)37[242:IVIRTE]2.0.CO;2 . PMID   18348816.
  16. ↑ Knight, Kathleen S.; et al. (2012). "Dynamics of surviving ash (Fraxinus spp.) populations in areas long infested by emerald ash borer (Agrilus planipennis)". Proceedings of the Fourth International Workshop on the Genetics of Host-parasite Interactions in Forestry: Disease and Insect Resistance in Forest Trees: 143–152.
  17. ↑ Koch, J. L.; Carey, D. W.; Mason, M. E.; Poland, T. M.; Knight, K. S. (21 June 2015). "Intraspecific variation in Fraxinus pennsylvanica responses to emerald ash borer (Agrilus planipennis)". New Forests. 46 (5–6): 995–1011. doi:10.1007/s11056-015-9494-4. S2CID   15947102.
  18. ↑ Stanley, Robert K.; Carey, David W.; Mason, Mary E.; Doran, Aletta; Wolf, Julia; Otoo, Kingsley Owusu; Poland, Therese M.; Koch, Jennifer L.; Jones, A. Daniel; Romero-Severson, Jeanne (24 July 2023). "Emerald ash borer (Agrilus planipennis) infestation bioassays and metabolic profiles of green ash (Fraxinus pennsylvanica) provide evidence for an induced host defensive response to larval infestation". Frontiers in Forests and Global Change. 6. Bibcode:2023FrFGC...666421S. doi: 10.3389/ffgc.2023.1166421 .
  19. ↑ "Fraxinus comparison chart". www.uwgb.edu. Retrieved 2018-11-11.
  20. ↑ "Injecting ash trees to protect from emerald ash borer". 6 July 2017.
  21. ↑ "One benefit of Minnesota's polar plunge: Ash borers took a licking". 31 January 2019.
  22. ↑ Edmonton: trees Archived 2007-09-27 at the Wayback Machine
  23. ↑ Arno, Stephen F.; Hammerly, Ramona P. (2020) [1977]. Northwest Trees: Identifying & Understanding the Region's Native Trees (field guide ed.). Seattle: Mountaineers Books. p. 283. ISBN   978-1-68051-329-5. OCLC   1141235469.
  24. ↑ Cook, Bill. "Forest management guidelines for Michigan". Michigan SAF Home Page. Michigan Society of American Foresters. Retrieved 5 July 2015.
  25. ↑ Liu, Houping; Bauer, Leah; Gao, Ruitong; Zhao, Tonghai; Petrice, Toby; Haack, Robert (2018-01-24). "Exploratory Survey for the Emerald Ash Borer, Agrilus Planipennis (Coleoptera: Buprestidae), and Its Natural Enemies in China". The Great Lakes Entomologist. 36 (2). doi: 10.22543/0090-0222.2093 . ISSN   0090-0222. S2CID   54088956.
  26. ↑ Orlova-Bienkowskaja, Marina J.; Drogvalenko, Alexander N.; Zabaluev, Ilya A.; Sazhnev, Alexey S.; Peregudova, Elena Y.; Mazurov, Sergey G.; Komarov, Evgenij V.; Struchaev, Vitalij V.; Martynov, Vladimir V.; Nikulina, Tatyana V.; Bieńkowski, Andrzej O. (2020-03-23). "Current range of Agrilus planipennis Fairmaire, an alien pest of ash trees, in European Russia and Ukraine". Annals of Forest Science. 77 (2): 29. Bibcode:2020AnFSc..77...29O. doi: 10.1007/s13595-020-0930-z . ISSN   1297-966X.
  27. ↑ "Ash Tree Identification". New York Invasive Species Information. Cornell University Cooperative Extension. Retrieved 5 July 2015.
  28. 1 2 3 Stephens, Jeffrey; Bervan, Keith; Tiegs, Scott (3 May 2013). "Anthropogenic changes to leaf litter input affect the fitness of a larval amphibian". Freshwater Biology. 58 (8): 1631–1646. Bibcode:2013FrBio..58.1631S. doi:10.1111/fwb.12155.
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