Invasive Plant Species

Scotch heather blankets many areas of the Lulu Island Bog	European birch and highbush blueberry have heavily invaded peatlands in Richmond	Purplse loosestrife is a significant invader in wetlands, and lines our ditches.

"Next to habitat loss, invasive species pose the greatest threat to the survival of native plants and animals in [Canada] and in many other parts of the world.  Invasive species are those plants, animals and microbes not native to a region which, when introduced either accidentally or intentionally, out-compete native species for available resources, reproduce prolifically, and dominate regions and ecosystems.  Because they often arrive in new areas unaccompanied by natural predators, these species can be difficult to control.  Left unchecked, many invasive [species] have the potential to transform entire ecosystems, as native species and those organisms dependent on them for food, shelter and habitat, disappear" (US National Management Plan, 2001).  

Richmond has a significant invasive species problem.  When we say this, though, what we really mean is that the two most urbanized and disturbed islands in the municipality have a significant problem::  Lulu Island and Sea Island, the two largest and most developed islands in the municipality. The other 22 islands in Richmond do support invasive plant species, but not to the extent that the urbanized islands do.

What species are the top problem species in Richmond?

On Lulu and Sea Islands, we find many of the plant species that are recognized as top invaders in the Metro Vancouver area, including

• Himalayan blackberry
• Japanese knotweed
• Scotch broom
• Giant cow parsnip/Giant Hogweed
• Purple loosestrife

Some of these species, such as Himalayan blackberry, literally blanket portions of the islands.  However, because these islands are located in the delta of the Fraser River, a lowland area based on silt depositions from the river, there are a few plant species that are particular problems here that are not problems throughout the rest of the Metro Vancouver area.   These are:

• European birch (a garden escape that blankets Lulu Island and is common in the Fraser delta)
• highbush blueberry (an escape from the blueberry fields that has also come to dominate our bogs)
• Scotch heather (another garden escape that blankets some of our boglands). 

Combating our top invasive species is going to take a concerted effort by groups, individuals, and municipal government.  The Greater Vancouver Invasive Plant Council in cooperation with Metro Vancouver Regional Parks, is already working on the Scotch broom invasion at Iona Beach Regional Park.  Now the onus is on the rest of us to 1) choose alternative species to plant in our gardens, 2) plant native species as much as possible, 3) discourage others from planting highly inavsive species.

This doesn't mean your garden can't be colourful.  Most garden plants are not invasive, so don't be afraid to plant all those colours you love. However, think twice about planting species such as Scotch heather or European birch, species that will readily invade our natural areas. If we can stop the inundation that is one big step towards recovery.  Garden species that are invasive, and that should be on our 'no plant' lists, include species that are easily dispersed by birds, such European mountain ash and English holly, or species that are wind-pollinated and that can hybrdize with our native species in natural areas around us.  Avoid plantings such well-known invasives as Scotch broom, false lamium, and others on the GVIPC list of unwanted plants.

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Page updated January 2009.  Contact us.