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© Jerzy Opioła
Fraxinus pennsylvanica - Red ash, Green ash

Synonym: Fraxinus pubescens
French name:  Frêne rouge
Family: Oleaceae
Group: Vascular plants
Origin: North America
Habitat: terrestrial
Introduction:  agri- and horticulture
ISEIA Score : 9
Naturalization in Belgium
First observation in the wild: 2008
Invasion stage: spread
Spatial distribution: isolated
Reproduction in the wild: yes
Dispersion potential: high
Natural habitats: likely
More on invasiveness: The green ash is a early- to late-successional species of riparian forests, adapted to survive in flooded soils through a variety of physiological and morphological traits. In Central Europe, it is mainly observed in riparian mixed forests of Quercus robur, Ulmus spp. and Fraxinus excelsior, along the great rivers (Ulmenion minoris, 91F0 Natura 2000 habitat), an habitat that nearly disappeared from Belgium. Green ash has been recently discovered as isolated individuals in other type of riparian habitats in Western Belgium, along rivers and canals. It is also known to easily colonize disturbed sites when a seed source is available, both in its native and introduced range. Seeds are wind dispersed; birds or small mammals may also aid dispersal by caching seed.
Distribution in Belgium
Established populations
absent from district
isolated populations (1-5 localities per district)
widespread (>5 localities per district)
Endangered areas
low risk
medium risk
high risk

Endangered Natura 2000 habitats ():
forest habitats: 91E0*91F0
Impacts on Species
Predation / Herbivory: low
Competition: likely
Disease transmission: low
Genetic effects: low
Impacts on Ecosystems
Nutrient cycling: unknown
Physical alteration: medium
Natural successions: medium
Food web alteration: low
More on impacts: The green ash can outcompete native species, overcome other trees and modify the vegetation structure in wide floodplains submitted to regular flooding events. It seems however to be less competitive in other riparian areas. As its preferred habitat is poorly represented in Belgium, green ash's capacity to cause environmental damages is uncertain. Plant extracts contain allelopathic compounds.
Data Source & References
Authors: Branquart Etienne, Vanderhoeven Sonia, Van Landuyt Wouter, Van Rossum Fabienne, Verloove Filip.
Published on:  23 July 2010
Last update:  11 March 2011
Botta-Dukát, Z. (2008)
Invasion of alien species to Hungarian (semi-)natural habitats.
Acta Botanica Hungarica 50(Suppl): 219–227.
Buttler, K.P. (2005)
Die Grün-Esche (Fraxinus pennsylvanica) an der Mainspitze eingebürgert.
Botanik und Naturschutz in Hessen 18: 15-22.
Csiszar, A. (2009)
Allelopathic effects of invasive woody plants species in Hungary.
Acta Silv. Lign. Hung. 5 : 9-17.
Gucker, C. L. (2005)
Fraxinus pennsylvanica.
In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer).
Krivanek, M. & Pysek, P. (2006)
Predicting invasions by woody species in a temperate zone: a test of three risk assessment schemes in Czech Republic.
Diversity and Distributions 12: 319-327.
Schmiedel, D. & Schmidt, P.A. (2010)
Fraxinus pennsylvanica Marsh. (Oleaceae), Rot- Esche
In: Kowarik, I (ed), Biologische Invasionen : Neophyten und Neozonen in Mitteleuropa.
Verloove, F. (2010)
Fraxinus pennsylvanica, Pterocarya fraxinifolia en andere opmerkelijke uitheemse rivierbegeleiders in België en NW-Frankrijk.
Walter, J. et al. (2005)
Neophytes in Austria: habitat preferences and ecological effects.
In: W. Nentwig et al. (eds), Biological invasions: form ecology to control. Neobiota 6: 13-25.

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