New Invasives Spread Rapidly in Canada

Recent assessments of invasive plants in Canada have given top rankings to plants that were not mentioned or were low on assessments made just twelve years ago. The rapid spread of the new invaders was a concern at the 2004 Canadian Botanical Association's second symposium on invasive alien plants in Canada. The quick expansion of the plants is an indication of the need for coordinated environmental monitoring programs and early detection of invaders.

An article in the Botanic Electronic News (BEN) describes five new plant invaders given the “worst” ranking in a recent survey of invasives:

• European Common Reed (Phragmites australis [Cav.] Trin. ex Steud. subsp. australis) - This foreign relative of the native (Phragmites australissubsp. americana) is considered Canada's number one invasive problem.


• Sea Buckthorn (Hippophae rhamnoides L.) - Introduced for its economic value, sea buckthorn has become a serious problem in the prairies where it forms monocultures driving out native species.


• Diffuse Knapweed (Centaurea diffusa Lam.) - A threat in British Columbia, this invader inhabits dry areas and can produce thousands of seeds per plant.


• Autumn Olive (Elaeagnus umbellata Thunb.) - Birds spread the fruit of this plant whose nitrogen-fixing ability upsets the balance of native soils.


• European Lake Sedge (Carex acutiformis Ehrh.) - Currently limited in area, this plant is difficult to distinguish from its native relative and thus can spread unnoticed.

Link: New “Top of the List” Invasive Plants of Natural Habitats in Canada from Botanic Electronic News (BEN). An excellent article with extensive references to resources on invasive plants in Canada.

Posted by Eric La Fountaine at 1:02 PM on April 14, 2005

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