Table 1.2e

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Table 1.2e Selected alien plant species associated with forests in Canada. (Sources: Hendrickson 2002; CBCN 1997; P. Catling, Agriculture and Agri-Food Canada, Ottawa, ON, personal communication, 2004)

Threat to	Common name	Type^a	Origin	Distribution	Invasive potential^b	Habitat/impact

Integrity of forest ecosystems	Norway maple	T	Eurasian	ON, QC, NL	L	Spreading from urban areas
	Garlic mustard	H	Eurasian	BC, ON, QC	H	Roadsides, open woods, near habitations. Outcompetes native species.
	Scotch broom	H	Europe	BC, NS, PEI	P	Sandy roadsides, barrens, open woods. Major problem in Garry oak ecosystems (BC).
	Tartarian honeysuckle	S	Asia	ON, NL, NS, NB, PEI	L	Forest edges. Displaces native understory and ground flora.
	White mulberry	T	Eurasian	ON	L	Waste areas, fence rows, forest edges (hybridzes with rare native red mulberry)
	Norway spruce	T	Eurasian	Eastern Canada	P	Forms dense evergreen story in moist deciduous woods.
	Scots pine, Scotch pine	T	Europe	BC, SK, AB, MB, ON, QC, NL, NB, NS, PEI	L	Old fields, roadsides, open bogs, open woods. Vector for European pine shoot beetle on neighboring jack and red pines (ON).
	Glossy buckthorn	S/T	Europe	MB, ON, QC, NB, NS, PEI	H	Displaces native species in wetlands, bogs, shaded ravines, and mixed woods (ON, QC, and local impact in Maritimes)
	English ivy	H	Europe	BC, ON	L	Fields, old gardens, urban areas. Kills mature trees (BC).
	Common gorse	S	Europe	BC	?	Occupies large patches, problem in Garry oak habitats (BC)
Natural regeneration or plantations	Silver birch, European white birch	T	Europe	BC, MB, ON, NS, PEI	L	Disturbed quarries and bogs, wetlands, or plantations (displaces native flora, overshades)
	Diffuse knapweed	H	Europe	YT, BC, AB, ON	P^c	Mountain meadows. Interferes with conifer survival and growth in interior of BC.
	Spotted knapweed	H	Europe	BC, AB, SK, MB, ON, QC, NL	P	Forms dense stands in mountain meadows
	Bull thistle	H	Eurasian	BC, SK	?	Establishes in lodgepole pine clearcuts
Urban forests or open areas	Wild chervil	H	Europe	NL, NS, NB, QC, ON, BC	?	Rich, moist soils. Forest edges, open forests, roadsides, waste areas. Often kills the surrounding vegetation by shading it.
	Ground ivy	H	Europe	BC, AB, SK, MB, ON, QC, NL, NB, NS, PEI	?	Forms dense carpets in riparian woodlands and aspen groves (SK)
	English holly	S	Eurasian	BC	?	Invades closed forests in greater Vancouver (BC)
	Privet	S	Europe	ON	P	Invades woodlands
	White poplar	T	Europe	BC, AB, SK, MB, ON, QC, NL	L	Beach habitats, urban areas (hybridizes with native poplars)
	European/common buckthorn	S/T	Europe	BC, SK, ON, QC, NS, PEI	H	Open woods, pastures, fence rows, forest edges (excludes native seedlings)
	Black locust, false acacia	T	USA	Southern Canada	L	Fence rows, roadsides, pastures, and moist woodlands
	Siberian elm	T	Asia	Frequently planted as urban tree	P	Open woodlands

^a T=tree; S=shrub; H=herb.
^b L=low level invasive; H=highly invasive; P=potentially invasive; ?=unknown (CBCN 1997).
^c Invasive potential inferred from Harris 2003.