Ruminations on Invasives …

As a student in Environmental Studies I feel like it has been drilled into me that invasive species are “bad”. Evil species hell bent on taking over the planet! I’ve been taught to shudder a little bit when I came face to face with English Ivy or Scotch Broom … At least I was. That all changed when I met Oliver Kellhammer. Oliver talked about how while it is important to value native species, it is not always realistic in the long run, or even moralistic. Humans have a tendency to idealize certain periods in history and Oliver suggested that this is the case with certain pre-colonial ecosystems on the West Coast. In fact, he argued that by idealizing these native plant-dominated ecosystems we are actively fighting against the natural push of evolution and change that occurs across every ecosystem over time. Moreover, we should keep in mind that not all so-called invasive species are so much invasive as they are “tropical” species that can bring new and different things to the ecosystem they now find themselves in. The term “tropical” was first used by Oliver during his talk and it is something that made me really start to re-think how I think about “invasives”.


Upon returning home from Linnaea I saw the English Ivy crawling up the rock face by my house and continued to puzzle over how we should think about these introduced species. I decided to do some research to see what other people had to say. As I looked, I found that there were many cases where, indeed, researchersare saying that these invasives, while not necessarily part of a native ecosystem, can be highly beneficial to the soil and native species in a region. Take, for instance, this article about the beneficial relationship that the local bird population forms with the honeysuckle plant in the Pennsylvania region ( or this article that provides a variety of other beneficial effects of invasives (

While I am certainly not saying that we should let Scotch Broom further proliferate across Vancouver Island and the west coast, there are certainly some positive impacts that invasives can have to an ecosystem. For instance, invasives can provide additional ecosystem services that native species cannot (as in the case with the honeysuckle plant in the previous paragraph), replenish regions that have been previously thought irrevocably damaged by humans (ruderal ecology), and even sustaining and adapting ecosystems that are struggling as a result of climate change. It is also important for us to remember that many plants and species that we know and enjoy are non-native in variety as well.

To be honest, I still don’t know how to feel on the issue. I am passionate about encouraging the return of native species around where I live and making sure that invasive species are not going to, as aforementioned, take over the world. However, I’ve found that my perspective on what “invasive species” are has been changed and I’m opening my mind to include the possible positive impacts that non-native species can have on our ecosystem.


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