How do we know which species are invasive in the Sea to Sky?
What makes a plant invasive is not just its own characteristics; it also depends on the environmental conditions where it grows.
A plant’s growing conditions include climate, soil nutrient levels, soil disturbance, the vigour of the existing native plant community and the presence of other lifeforms (e.g., mammals, insects, funghi, etc.), to name a few. For example, the invasive yellow flag iris thrives along the Sea to Sky’s many streams, rivers and water bodies, but it would struggle to invade the dry conditions of an arid desert. Just because a species is invasive here, doesn’t always mean it is invasive elsewhere!
Several factors influence whether a non-native species will become invasive
Yellow flag iris is an aquatic invasive that grows in rivers and sloughs in the Sea to Sky.
At SSISC, we work closely with biologists, stakeholders, and community members to assess which species are invasive in our region and which ones should be added to our priority list. We also rely on observation and research: when we notice a non-native species spreading rapidly, harming people, or impacting our local habitat and biodiversity, it’s an indicator that the species is likely invasive to our region.
Invasive species don’t conform to borders and regional boundaries
If given the opportunity, invasive species will spread anywhere they find favourable conditions. The chances are, if a species is invasive in the Sea to Sky, it’s likely a concern in other parts of BC and even throughout North America.
Invasive species as an environmental issue go well beyond the Sea to Sky region, so the best ways to manage these invasives often go beyond just our region, too. While SSISC works exclusively in the Sea to Sky, we collaborate with other regional invasive species organizations (RISOs) to better understand the broader impacts of invasives, promote province-wide campaigns, and develop province-wide solutions. This collaboration also allows us to be on the lookout for species that have become a problem in other parts of BC.
The level of invasiveness can even differ from one area to another within a region
English ivy is a common invasive species in Squamish.
Even within the Sea to Sky, we can observe differences in the way invasive species ‘behave’. Take English ivy for instance: it is extremely invasive in Squamish and south and is found in many parks and gardens. However, it’s not commonly found in Whistler and north; this is due in part to colder winters, which limits ivy’s ability to spread as rapidly.
Don’t be mistaken – English ivy is invasive throughout the Sea to Sky region, but a notable difference in invasiveness is observed within a stretch of 60km and 600 meters of elevation between Squamish and Whistler.
All that to say…
Whether a species becomes invasive (and to what extent) ultimately depends on both the species’ inherent traits and its environment. While the Sea to Sky region has a diverse geography, invasive species don’t adhere to these boundaries and are likely to spread to any habitat that favours them. That’s why SSISC collaborates with other regional invasive species organizations within the province and beyond, sharing knowledge and coordinating efforts to address this widespread issue.
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