Native here, Invasive there

Native here, Invasive there
Native here, Invasive there

What are some species that are native to North America, but invasive in other parts of the world?

At SSISC, we spend most of our efforts tackling invasive plants or animals living in the Sea to Sky, but did you know many of our native species are invasive outside of BC?

While these plants or animals live harmoniously with our local environment, they can cause harm when brought to other places.

Common Horsetail (Equisetum arvense)

Horsetail, although deemed undesirable and regarded as a weed in certain contexts, is native to BC. While Common Horsetail is frequently found in the Sea to Sky, there are over 30 species in the horsetail group which share the genus Equisetum. This plant family is native to temperate parts of Europe, North America as well as Asia. Unfortunately, its ability to spread quickly has made it an aggressive invader in the UK, Australia, and New Zealand. It spreads vegetatively through its creeping rhizomes and forms dense patches of foliage that crowd out other plants.

Photo: W. Siegmund

Skunk Cabbage (Lysichiton americanus)

It may be stinky, but Skunk Cabbage plays an important role in the Sea to Sky as a food source for bears and for its medicinal uses in Indigenous cultures. This plant was introduced as an ornamental in Europe for its bright, yellow ‘flowers’, and escaped cultivation to invade European stream sides, bogs and wet woodlands. Its large leaves and dense stands block out light and prevent native species from growing. Not only that, but its seeds can remain viable in the soil for over 8 years, which makes controlling this plant a long and lengthy process.

Lupin Lupinus sp.)

Did you know these beautiful native flowers are invasive in New Zealand? They were originally brought to the island as ornamentals and were also found to be nutritious food for sheep, which was convenient because lupins needed little fertilizer. However, these gorgeous plants colonize streambanks and take over habitats that are important for native wildlife. Despite their invasive tendencies, the beautiful lupins still attract tourists to Lake Tekapo, New Zealand, from around the world.

Lupins have stirred up quite a controversy in New Zealand, as many believe that the plant positively impacts tourism and agriculture, however, it still causes immense harm to the local environment.

Photo: D. giles

Salal (Gaultheria shallon)

Salal fills a great niche here in the Sea to Sky – it is shade tolerant and is a common understory plant in conifer forests of the Pacific Northwest. It was introduced to Britain as an ornamental plant and quickly established itself as an invasive species in many parts of Europe, including the UK, France, Ireland, and the Netherlands. Mechanical removal of Salal is ineffective, as it risks breaking up its rhizomes and has the potential to stimulate new growth. Its waxy foliage also makes it resistant to many herbicides. Biological control may be effective though – in the UK, consumption by cattle has been found to reduce Salal populations.

North American Beaver (Castor canadensis)

In BC, the North American beaver is often perceived as an industrious dam-building creature, but it can be extremely invasive in other parts of the world. In 1945, 50 beavers were introduced to Tierra del Fuego, an area on the southern tip of Patagonia, as a source of commercial fur trading. However, the prospects for the fur industry soon dissolved and the beavers have remained to wreak havoc ever since. They have no natural predators in Patagonia, which allowed their population to grow exponentially to an estimated 100,000 beavers or more.

One study on the situation in Tierra del Fuego describes the beaver impacts as “the largest landscape-level alteration in subantarctic forests since the last ice age” (read here). Their creation of dams has led to significant structural changes in the landscape, including accumulating nutrients in rivers and streams, and the destruction of riparian trees. Currently, the governments of Chile and Argentina are attempting to eradicate the North American beaver from the area, which may be the largest eradication project ever attempted.

Photo: R. Hodnett
Photo: Rhododendrites

Raccoon (Procyon lotor)

Some people think they’re cute, while others think they’re pests – especially when they break into garbage cans and are a general nuisance. Raccoons can be annoying here in North America, and they’re considered invasive in Japan and Germany.

How on Earth did they get there? In 1977, an anime cartoon series called Rascal the Racoon was released in Japan, which told the story of a young boy and his sidekick raccoon who went on adventures together. The show was a huge hit – and many Japanese families adopted baby raccoons as pets. Unfortunately, as the raccoons grew older, families found the adult raccoons too large and aggressive to keep at home, and released the raccoons into Japan’s forests. (This is a prime example of why you shouldn’t release your pets – check out Don’t Let it Loose to learn more!).

As an established invasive species in Japan, they eat crops and native species. They have also damaged many local temples. It is estimated that raccoons have caused $275,000 USD of agricultural damage in Hokkaido alone.

In Germany, raccoons were intentionally released as a way to increase fauna diversity. As they have no natural predators, their populations grew greatly – by 2012, it was estimated that Germany had over 1 million raccoons. They are huge pests – threatening bird populations and outcompeting native species.


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