Invasive Species by Adrian Avendano

October 16, 2024 Nora Boekhout

Invasive Species presentation by Adrian Avendano of the Invasive Species Council of Metro Vancouver
October 16, 2024, BC Fuchsia and Begonia Club
Thank you to Larry Mroz for writing this report.

Adrian began with a territorial land acknowledgement and recommended a City of Burnaby Indigenous history source for those interested in learning more.

Introduction to invasive species: What is an invasive species? Adrian explained that it is a non-native species, (native to elsewhere), that can cause significant harm to a new environment in that it ‘takes over’ by displacing native species. There are currently 120 species that are considered invasive (in BC) plus 100 more that are more recently introduced. They are treated differently as pests, depending on what harm they do to the environment and how they grow. Some examples are ivy, hogweed, bullfrogs and fire ants.

Impacts of Invasive Species Can be:
Ecological: In unmanaged or wild or natural systems an invasive plant can displace native plants and become a monoculture – for example purple loosestrife in wetlands. It uses all the space and resources so native plants can’t grow. Native plants provide resources to other organisms that the invasive plant doesn’t provide therefore disrupting the entire ecosystem – disrupting the balance and causing drastic changes to the species that live there. For example, the pollen produced by purple loosestrife is less nutritious for pollinators which can affect future generations of pollinators negatively (more prone to disease, more difficulties to reproduce etc.)

Health and Safety: Hogweed has an irritant on its surface – photoactive compounds that can get on your skin and cause burns in sunlight. Chemical reaction can cause serious skin damage. It can prevent people and animals from accessing the area, which additionally creates social/cultural damage for indigenous peoples.

Economic: There are 3 types of knotweed, which are very expensive to control. Digging doesn’t help because it breaks up the roots and stems which can regenerate into new plants. It causes damage to roads and foundations. Controlling these plants needs expensive chemicals and much labour. It takes years to eradicate- at least 5-7 years, even 11 years in one case. BC spends millions to try to control knotweed. It is in the top 3 on the priority list of invasive species in BC.

Climate change can make invasive species even worse! When natural areas and species are damaged, the results favour invasive species that can adapt to warmer weather and drought/heavy rain. An example of this: An invasive grass in Hawaii has taken over and is more susceptible to fires. It displaced native fire-resistant grass and then when fire happened it was much worse than usual. The invasive grass supplied more fuel, making the fire more intense and damaging.

Where do Invasive Species come from and how do they get here? Unfortunately, the Port of Vancouver is a major source. Also, some garden centres might sell some of them since there aren’t sufficient laws to stop them. They can hitchhike as seeds or roots in potting soil or nursery plants, and can be spread by birds and animals, construction and development spreads roots.

Solutions? Education, prevention and mediation: Herbicide is often the best answer despite the bad rep and potential for pollution. It is worth the risk if they are applied correctly and safely. Biological controls may also be a good choice. This involves bringing in a species that is a predator of the invasive species. For example, some weevil species control invasive plants. This must be done carefully to ensure native species are not attached or harmed. Ideally the biological agent will just eat the invasive species and then die out with it. Another solution might be Cultural control: Find uses for the invasive plant, such as harvesting it for cultural or economic use.

Some examples of invasive species: Knotweed has at least 3 species: Japanese, giant and bohemian. It was originally planted as an ornamental garden plant and now it grows everywhere. Others include: Himalayan blackberry, Red canary grass, Yellow archangel or lamiastrum, Scotch broom (one plant can produce 30000 seeds in a summer so it is a great spreader), Yellow flag iris, Parrots feather (an aquatic weed), Eurasian water millfoil (which can deoxygenate water),Tree of Heaven, (Ailanthus) or Chinese sumac. This last one is new to BC and grows in poor soil. It’s a host tree for spotted lantern fly which is another invasive species, so combined they could cause significant economic damage to many plant species.

Adrian discussed several more invasive plants which are available to view on the ISCMV website. He also mentioned some invasive insects to worry about. The Japanese beetle is currently restricting movement of any soil or plants out of Port Coquitlam. The Emerald Ash borer, new in May 2024, is a huge concern because it kills ash trees very quickly and about 20% of Vancouver street trees are ash. The potential damage is enormous (at least 10,000 trees in the City of Vancouver alone).

Adrian advised us that, as responsible gardeners, we should replace any invasive plants in our gardens with native plants such as red elderberry, Oregon grape, red-flowering currants or vine maple. Also, if you see an invasive species, report it on the council’s website or get the Report Invasive App for your phone. Reaching out directly to local government regarding invasive species issues is also recommended.

Thank you, Adrian for this important and informative presentation.
You can be sure we will all be looking out for invasive species in our area!