In the midst of the sixth mass extinction, care is a radical concept. The distinct nature of the present environmental problems is that they are driven by human activities. And invasive species are no exception. But, do invasive species deserve our finite attention amongst the chaos of wildfires, mass floods, and record-breaking heatwaves? Dr. Nina Hewitt, a biogeographer specializing in plant dispersal, migration and disturbance ecology, says yes. She sat down (virtually) with us to share her views.
Ignorance is bliss
Japanese Knotweed infestation
Just as global warming is rooted in human activities, so too is the issue of introduced invasive species.
As Dr. Hewitt notes, 
human mobility has fundamentally altered the make-up and the character of the biological world, as more and more species have been introduced, either intentionally or unintentionally, into non-native ecosystems. This phenomenon, on the rise ever since the age of exploration, has accelerated dramatically in relatively recent times, with the advent of mass transportation, agriculture, travel, and trade.
Dr. Hewitt describes invasive species as “plants, animals or pathogens, that become established in a new environment and spread in ways that are destructive to human interests and natural systems.” Indeed, they are known to “alter community composition, trophic pathways, native species distribution, habitat, and even the evolutionary fitness of native species,” says Dr. Hewitt. But the impacts of invasive species extend beyond ecological harm, with adverse effects on culture, food security, human health, and national economies. For instance, a subset of just 16 (out of 1400 identified) invasive species in Canada has an estimated economic impact of $13-35 billion CAD annually.
Giving nature a helping hand
“It requires an adaptive management approach, a lot of longer-term research on what is happening, and a little bit of risk-taking.”
If humans are the culprit, why not allow nature to ‘restore’ itself? Well, as surprising as it may seem, the natural environment is in a constant state of flux.
The Disney-fied notion that left to its own devices, nature will always revert to an idyllic equilibrium is a dangerous fallacy, explains Dr. Hewitt. It is a belief system that has burrowed deep in our psyches and may be hindering our ability to consider the consequences of inaction.
“The ‘balance of nature’ ideology becomes a problem because it leaves you with this hands-off approach; that nature will bring itself back to the necessary condition on its own,” Dr. Hewitt continues, adding that “in grad school, we began to recognize that we actually do need to manipulate, control, and remove species that are undesirable, especially if they are invasive because they have the upper hand.”
So, instead of debating whether humans should interfere, the dialogue should focus on which human interventions should be promoted and which should be opposed. As Dr. Hewitt proposes, “It requires an adaptive management approach, a lot of longer-term research on what is happening, and a little bit of risk-taking.”
A Case Study: Climate Change and Invasive Species
“Sometimes, succession towards a new standard vegetation is about arrival…”
Of all the various pressing environmental concerns, which should we address? According to Dr. Hewitt’s research, we don’t necessarily have to choose.
Forest affected by pests and diseases
Climate change and invasive species are connected in many ways, with climate change opening up new habitats for invasive species, and invasive species making ecosystems more vulnerable to environmental change.
“Changing climate conditions will mean that invasive species, who tend to be generalists, reproduce rapidly, disperse very effectively, and take advantage of longer growing seasons, will now survive and colonize successfully in locations that were once too cold,” says Dr. Hewitt. She adds that “Sometimes, succession towards a new standard vegetation is about arrival, and who gets there first, so if you are a species that is predictively good at dispersal and colonization, chances are you will colonize new sites before many other species.”
Indeed, invasive species will also benefit from new niches becoming available if native species are no longer adapted to changing climate conditions.
Moreover, as climate change alters human movement, for instance, by opening new trade routes with the melting of the Arctic sea ice, current and potential invaders have more opportunities to reach new sites through various pathways.
At the same time, invasive species make ecosystems and communities more vulnerable to disturbances and the impacts of climate change.
For example, healthy forests are carbon sinks that capture and store large amounts of atmospheric carbon. However, the spread of the invasive White Pine Blister Rust kills several native pine species, turning forests into a carbon source, as killed trees release stored carbon back into the atmosphere – further accelerating climate change.
Thus, addressing one environmental concern may indirectly have positive effects on the other. Nonetheless, a comprehensive solution hinges on confronting the two in tandem and recognizing they are signals of the same systemic issue.
The stakes are high
“I think that in order to shift, it becomes political.”
Undoubtedly, there are many reasons to care about invasive species. But caring is not just a feeling or a sentiment; it is an action. It is the discipline of showing up for the collective good.
As Dr. Hewitt says, “At a small level, I think anybody that is involved in managing natural or semi-natural areas has to be concerned about invasive species just because in many cases, without attention and some activities associated with control, you basically lose that natural area.” She continues, adding that “from a larger standpoint, it all is about human activities and our corporate approach to the world. This idea is that the kinds of ways of life that we have decided are normal are simply unsustainable: the single-family automobile, travelling internationally and importing goods globally. I think that in order to shift, it becomes political. It becomes about ordinary citizens, changing who they vote for, continually lobbying, and working for a change in the structure of our economy from this kind of capitalistic growth-dominated economy to one that is not as disruptive.”
We know that the time for this great transition is short. Environmental experts have told us that this is the decade to take decisive action to prevent catastrophic environmental changes.
While it may not feel like it, every time we remove an invasive species is a victory. Every time we protect a rainforest is a victory. Every time we decide to care, it is radical.
Nina Hewitt
Nina Hewitt graduated from York University with a Ph.D. in Biogeography and is currently a Professor at the University of British Columbia. Her research examines vegetation dynamics and the environmental impacts of human activities, such as ecosystem fragmentation, altered disturbance regimes, biological invasions, and climate change, with the intent to find solutions to manage these impacts. Visit her research website to learn about her current and recent projects.
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