Fraxinus pennsylvanica Marshall (N-Am.) – A very rare but increasing escape from cultivation. First recorded in the wild in Belgium in 2008 when it was found on several occasions in the provinces of West- and East-Flanders, mostly in riparian habitats, for instance of rivers Leie and Schelde (Verloove 2011). Soon afterwards it was also repeatedly seen alongside the Kempisch Kanaal in the surroundings of Geel. It is occasionally seen elsewhere, usually in close proximity of planted individuals. Fraxinus pennsylvanica is mostly seen as single individuals but in some instances abundant saplings have been recorded.
The naturalization and spread of Fraxinus pennsylvanica is well-documented in some Central European countries, for instance in Germany (e.g. Buttler 2005, Schmiedel 2011 and numerous additional references, for which see below). In Bremen its invasion started already soon after World War II (Albrecht & al. 2014).
The Pennsylvanica Group is shown as monophyletic but a clear morphological synapomorphy is not evident (Nesom 2014). The separation of members of this group therefore is often difficult. Belgian populations of Fraxinus pennsylvanica are sometimes close to F. americana L.
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Selected literature:
Achinelli F.G. & Delucchi G. (1999) El "fresno americano" presente en la Argentina es Fraxinus pennsylvanica (Oleaceae). Bol. Soc. Argent. Bot. 34(1-2): 11-15. [available online at: https://www.researchgate.net/publication/262602647_El_fresno_americano_p...
Achinelli F.G. & Delucchi G. (2000) El "fresno americano" naturalizado en la Provincia de Buenos Aires (Argentina): Fraxinus pennsylvanica Marshall (Oleaceae). Rev. Mus. La Plata, Bot. 14(110-113): 477-482. [available online at: https://www.researchgate.net/publication/262602390_El_fresno_americano_n...
Albrecht B.M., Lietsch V. & Zacharias D. (2014) Die Rot-Esche (Fraxinus pennsylvanica Marsh.): Ein im Stadtwald Bremen eingebürgerter Neophyt. Mitt. Deutsch. Dendrol. Ges. 99: 13-24.
Black-Schaefer C.L. & Beckmann R.L. (1989) Foliar flavonoids and the determination of ploidy and gender in Fraxinus americana and F. pennsylvanica (Oleaceae). Castanea 54(2): 115-118.
Boeuf R. (2003) Un frêne exotique méconnu en Alsace et plus largement en France: le frêne de Pennsylvanie (Fraxinus pennsylvanica Marschall (sic) – Oleaceae). Bull. Soc. Bot. Centre-Ouest N.S. 34: 169-174.
Botta-Dukát Z. (2008) Invasion of alien species to Hungarian (semi-)natural habitats. Acta Botanica Hungarica 50(Suppl): 219-227. [available online at: http://www.akademiai.com/doi/abs/10.1556/ABot.50.2008.Suppl.11?journalCo...
Buttler K.P. (2005) Die Grün-Esche (Fraxinus pennsylvanica subsp. novae-angliae) an der Mainspitze eingebürgert. Botanik und Naturschutz in Hessen 18: 15-22.
Campbell J.J.N. (2017) Green/red and white ashes (Fraxinus sect. Melioides) of east-central North America: Taxonomic concepts and polyploidy. Phytoneuron 2017-28: 1–36. [available online at: http://www.phytoneuron.net/2017Phytoneuron/28PhytoN-Fraxinus.pdf]
Drescher A. & Prots B. (2016) Fraxinus pennsylvanica - an invasive tree species in Middle Europe: case studies from the Danube basin. Contr. Botanice LI: 55-69. [available online at: https://www.researchgate.net/publication/313821796_FRAXINUS_PENNSYLVANIC...
Gausmann P., Haeupler H. & Adolphi K. (2017) Verwilderungen von Aralia elata, Fraxinus pennsylvanica und Juglans ailantifolia im Mittleren Ruhrgebiet (Nordrhein-Westfalen). Florist. Rundbr. 51: 108-127. [available online at:https://www.researchgate.net/publication/324029802_Verwilderungen_von_Ar...
Nesom G.L. (2014) Phylogeny of Fraxinus sect. Melioides (Oleaceae): Review and an alternative hypothesis. Phytoneuron 2014-95: 1-9. [available online at: http://phytoneuron.net/2014Phytoneuron/95PhytoN-FraxinusCommentary.pdf]
Reichhoff L. & Eichhorn A. (2008) Wird die Rot-Esche zum Problem an der Elbe? : Die amerikanische Baumart vermehrt sich auf Kosten einheimischer Bäume. Fachleute diskutierten auf einem Workshop die möglichen Auswirkungen. Naturschutz im Land Sachsen-Anhalt 45(1): 60-61. [available online at: http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/year/2014...
Reichhoff L. & Reichhoff K. (eds.), Die Rot-Esche : (Fraxinus pennsylvanica) ; eine invasive Baumart in den Hartholzauenwäldern des Mittelelbegebietes? Dessau-Roßlau: LPR Landschaftsplanung Dr. Reichhoff: 72 pp.
Schaffrath J. (2001) Vorkommen und spontane Ausbreitung der Rotesche (Fraxinus pennsylvanica Marshall) in Ost-Brandenburg. Naturschutz und Landschaftspflege in Brandenburg: Beiträge zu Ökologie, Natur- und Gewässerschutz 10(4): 134-139.
Schmiedel D. (2010) Fraxinus pennsylvanica in den Auenwäldern der Mittelelbe: Invasionsbiologie und ökologisches Verhalten im naturschutzfachlichen Kontext. Berliner Beiträge zur Ökologie 6.
Schmiedel D. (2011) Ausbreitungsökologie und Etablierung der Rot-Esche (Fraxinus pennsylvanica Marsh., Oleaceae) in den Auenwäldern der Mittleren Elbe (Sachsen-Anhalt). Mitt. Deutsch. Dendrol. Ges. 96: 105-118.
Schmiedel D., Huth F. & Wagner S. (2013) Using data from seed-dispersal modelling to manage invasive tree species : the example of Fraxinus pennsylvanica Marshall in Europe. Environmental Management 52(4): 851-860. [available online at: https://www.researchgate.net/publication/256101212_Using_Data_From_Seed-...
Schmiedel D. & Schmidt P.A. (2010) Fraxinus pennsylvanica Marsh. (Oleaceae), Rot- Esche. In: Kowarik I. (ed.), Biologische Invasionen: Neophyten und Neozoen in Mitteleuropa. Available online at: https://www.researchgate.net/publication/270892915_Biologische_Invasione...
Schönbrodt R. & Jurgeit F. (2008) Wie umgehen mit der Rot-Esche in den Schutzgebieten Sachsen-Anhalts? Naturschutz im Land Sachsen-Anhalt 45(2): 57-59. [available online at: http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/31876]
Steen D.A., Heaney S., Ehrle E.B. & Thompson P.W . (1996) The big trees of Michigan: 11. Fraxinus pennsylvanica L. Mich. Bot. 34(4): 144-146.
Taylor S.M. (1971) Ecological separation and post-settlement habitat changes of Fraxinus americana and Fraxinus pennsylvanica in Washtenaw County, Michigan. Amer. J. Bot. 58(5): 466-467.
Taylor S.M.O. (1973) Ecological and genetic isolation of Fraxinus americana and Fraxinus pennsylvanica. Diss. Abstr. Int., B 33(11): 322 pp.
Verloove F. (2011) Fraxinus pennsylvanica, Pterocarya fraxinifolia en andere opmerkelijke uitheemse rivierbegeleiders in België en NW-Frankrijk. Dumortiera 99: 1-10. [available online at: http://www.br.fgov.be/DUMORTIERA/DUM_99/Dum%2099_1-10_Fraxinus%20pennsyl...
Zacharias D. & Breucker A. (2008) Die nordamerikanische Rot-Esche (Fraxinus pennsylvanica MARSH.): zur Biologie eines in den Auenwäldern der Mittelelbe eingebürgerten Neophyten. In: Evers C. (ed.), Dynamik der synanthropen Vegetation : Festschrift für Prof. Dr. Dietmar Brandes. Braunschweiger Geobotanische Arbeiten 9: 499-529. [available online at: http://rzbl04.biblio.etc.tu-bs.de:8080/docportal/servlets/MCRFileNodeSer...