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© Etienne Branquart
© Etienne Branquart
© Etienne Branquart
Mahonia aquifolium - Oregon grape

Synonym: Berberis aquifolium
French name:  Mahonia faux-houx
Dutch name: Mahonia
Family: Berberidaceae
Group: Vascular plants
Origin: North America
Habitat: terrestrial
Introduction:  agri- and horticulture
ISEIA Score : 12
Naturalization in Belgium
First observation in the wild: 1906
Invasion stage: spread
Spatial distribution: restricted
Reproduction in the wild: yes
Dispersion potential: high
Natural habitats: high
More on invasiveness: Since a few years, Mahonia is increasingly observed in the wild in Belgium. Its exact identity is uncertain but most populations probably belong to hybrids with the related M. repens and M. pinnata characterised by a strong suckering capacity (= horticultural cultivars that are often planted in parks and gardens). Feral populations occur in a wide range of semi-natural habitats like dunes, rock outcrops, grasslands and woodlands. They prefer calcic soils and can grow in dry to moist conditions, often in shaded habitats. Mahonia produces numerous flowers and berries that are dispersed by birds over long distances. The recent expansion of this species in Western Europe is probably triggered by climate warming.
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 ():
dune habitats: 21102130*21702180
sclerophyllous scrub: 51105130
grasslands: 6110*6210*
rocky habitats: 8160*
forest habitats: 9150
dune habitats: 2160
Impacts on Species
Predation / Herbivory: low
Competition: high
Disease transmission: low
Genetic effects: low
Impacts on Ecosystems
Nutrient cycling: unknown
Physical alteration: high
Natural successions: high
Food web alteration: low
More on impacts: Mahonia aquifolium has a high growth rate due to hybridization and subsequent selection by breeders. Rapid clonal growth takes place through root suckers and stem layering, leading to the formation of large and dense populations that are known to overgrow and outcompete native species and accelerate the colonisation of open habitats by woody vegetation. The species is especially known to produce dense monospecific populations in the coastal dunes in Belgium.
Data Source & References
Authors: Branquart Etienne, Vanderhoeven Sonia, Van Landuyt Wouter, Van Rossum Fabienne, Verloove Filip
Published on:  04 December 2007
Last update:  17 December 2010
AEF (2006)
Cartes provisoires de la distribution de néophytes en Wallonie.
Unpublished document.
Auge, H. & Brandl., R. (1997)
Seedling recruitment in the invasive clonal shrub, Mahonia aquifolium Pursh (Nutt.)
Oecologia 110: 205-211.
Keil, P. & Loos G.H. (2005)
Preliminary account of ergasiophygophytic and xenophytic trees, shrubs and subshrubs in the Central Ruhrgebiet (Germany).
Electronic Publications of the Biological Station of Western Ruhrgebiet 3: 1-12.
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.
Lambinon, J., Delvosalle, L. & Duvigneaud, J. (2004)
Nouvelle fore de la Belgique, du Grand-Duché de Luxembourg, du Nord de la France et des régions voisines.
Editions du Patrimoine du Jardin botanique national de Belgique, Meise.
Lohmeyer, W. & Sukopp, H. (2001)
Agriophyten in der Vegetation Mitteleuropas.
In: Brandes, D. (ed.) Adventivpflanzen. Beiträge zur Biologie, Vorkommen und Ausbreitungsdynamik von Archäophyten und Neophyten in Mitteleuropa, vol 8. Universitätsbibliothek Braunschweig, Braunschweig, pp 179-220.
Ross, C.A. & Auge, H. (2008)
Invasive Mahonia plants outgrow their native relatives
Plant Ecol. 199: 21-31.
Ross, C.A., Faust, D. & Auge, H. (2009)
Mahonia invasions in different habitats: local adaptation or general-purpose genotypes?
Biological Invasions 11: 441-452.
Van Landuyt, W., Hoste, I., Vanhecke, L., Van den Bremt, P. Vercruysse, W. & De Beer, D. (2006)
Atlas van de Flora van Vlaanderen en het Brussels gewest.
Nationale Plantentuin en het Instituut voor Natuur- en Bosonderzoek i.s.m. Flo.Wer vzw.
Verloove, F. (2006)
Catalogue of the Neophytes in Belgium (1800-2005).
Scripta Botanica Belgica 39, 89 pp.
Walther, G.-R (2004)
Plants in a warmer world.
Perspectives in Plant Ecology, Evolution and Systematics 6/3: 169–185.
Walther, G.-R. (2002)
Weakening of climatic constraints with global warming and its consequences for evergreen broad-leaved species.
Folia Geobotanica 37: 129-139.
Walther, G.R. (2000)
Climatic forcing and the dispersal of exotic species.
Phytocoenologia 30(3-4): 409-430.
Wittenberg, R. (2005)
An inventory of alien species and their threat to biodiversity and economy in Switzerland.
CABI Bioscience Switzerland Centre report to the Swiss Agency for Environment, Forests and Landscape. The environment in practice no. 0629: 155p.

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