‘It’s not invasive in my yard’: How invasive plant species harm biodiversity
Chronicle gardening columnist Christina Keys explains the impact of invasive plant species on the surrounding ecosystem
Periwinkle, creeping bellflower, day lily, lily of the valley, goutweed, common buckthorn, and Siberian squill are among the invasive plants that Dave Keys of Lonsdale Rd.had in his backyard. They ran wild, taking over the beautiful giant hostas, peonies, Siberian irises, and even the native trout lilies. Yet the greatest harm happens when invasive plants inevitably escape yards and invade natural areas.
Invasive species are harmful non-native plants that outcompete native species, creating a dead zone of vegetation that does not support the local insects, birds, and mammals that rely on native plants.
Most invasive plants are introduced to wild ecosystems through landscaping. Some plants we buy at our local garden centre escape our yards to invade natural areas. Birds eat the seeds and deposit them in other areas, and wind blows the seeds away.
Some people feel that invasive plants do no harm when confined to their own gardens or yards. However, even the most diligent gardener cannot control an invasive species.
Why are these plants even for sale if they do such harm? Very few plants in the horticultural trade are regulated in Canada, despite the enormous cost to all levels of government, to the agricultural sector, and to biodiversity. The Canadian Coalition for Invasive Plant Regulation is trying to change this by lobbying at the federal level for regulations to limit the sale of these harmful species.
In our neighbourhood, it is not hard to see the devastation caused by invasive species in our natural spaces, but gardeners and landscapers can make a huge difference. (A recent bylaw amendment by the City of Ottawa allows curbside gardens yet bans the presence of invasive plant species.)
You can help alleviate the biodiversity crisis by removing invasive species from your yard.
Ontario’s Invading Species Awareness Program has excellent visual guides for invasive species and, combined with an app like Picture This or PlantSnap, you’ll easily be able to identify them and learn how to effectively remove them. You can talk to your landscaper, landlord, or condo association about their management of invasive species and provide them with these resources.
Transforming ‘ecological dead zones’
Identifying and removing invasive plants is the hard part. The fun part is replacing these harmful species with beautiful, non-invasive alternatives or even beneficial native plants. The Manor Park Community Association has the Native Plant Demonstration Garden located at 100 Thornwood Ave. for inspiration if you have similar sunny, dry conditions.
It may take a few years of diligence for the lily of the valley and the periwinkle to be fully eradicated from Dave’s shady yard. He’s removed them along with all the other invasive species and replaced them with native wood poppy, woodland strawberry, Canada anemone, cardinal flower, blue lobelia, Joe Pye weed, morning star sedge, and bottlebrush rye grass.
He’s still waiting for the first hummingbird, but over the coming years, the yard will be transformed from an ecological dead zone into a thriving, beneficial ecosystem.
Common Invasive Species in Manor Park
- Burning bush
- Common buckthorn
- Creeping bellflower
- Day lily
- Dog-strangling vine
- English ivy
- Garlic mustard
- Japanese knotweed
- Lily of the valley
- Norway maple