Maybe All Invasive Species Aren’t Terrible?

Different species aren’t inherently bad. Studies have shown that the effects of some non-native species are neutral, or even positive. One example I recently learned of is garlic mustard, a species that people spend a lot of effort trying to eradicate, and how the flowering plant might fare in a changing climate.

“Momentary Repose” by harefoot1066 is licensed under CC BY-ND 2.0 

Invasive species have been referred to as ‘exotic’, ‘noxious’, ‘foreign’ and other terms that paint them in a certain light without providing much detail. An article in Smithsonian Magazine proposed the idea that some ‘invasive’ species, such as the Tamarisk shrub in the American southwest, bring ecological value to their new habitat. The Tamarisk was seen as a cancer for many years, not unlike other non-native species. When conservationists realized the shrub’s ability to house endangered songbirds, that perspective was flipped. But what would have happened if we used a more positive descriptive terminology for invasive species in the first place?

“Giant Tortoise” by D-Stanley is licensed under CC BY 2.0 

The Giant Tortoise in the Galapagos prefers to eat introduced species of vegetation that provide more calories and nutrition than alternative native plant food. For the island nation of Mauritius, bringing in the Giant Tortoise as a non-native species served the purpose of replacing the extinct native tortoise. The tortoises also should aide in seed dispersal for native woody plants. A different type of turtle, the wattle-necked softshell turtle, was introduced to the island of Kauai in the 1850’s by Chinese farmers who ate them in soup. Now, the population in China is endangered, but the turtles in Kauai are doing well. There is some concern that the turtles might feed on native fish. Still, the island remains their only option aside from extinction. Other non-native species have similar stories that defy the ‘toxic’ ‘damaging’ and ‘harmful’ narrative, such as Hippos in Colombia, red-crowned Amazon parrots in Hawaii, and spartina grass in California.

cattail plant
Photo by Emily Hopper on

Another scientific study in Frontiers in Environmental Science (an open access journal) highlighted the nutrient stocking capability of the non-native wetland reed Phragmites Australis, which has been overwhelmingly successful in the United States. The reed will absorb nutrients from the surrounding environment and hold it in biomass and soil, which is beneficial to ecosystems like the Great Lakes where nutrient buildup causes eutrophication, which then suffocates fish and spawns algal blooms. Although P. Australis-dominated wetlands will retain more nutrients than meadow marshes, there is not a noticeable change in biomass, carbon or nutrient standing stocks when the reed takes over cattail marshes. The authors suggest reviewing the original vegetation type, difference in nutrient retention as a result of non-native species takeover, and the harm done to biodiversity and habitat value when making a decision about invasive species control.

Now let’s talk about word choice. Rhetoric undoubtedly matters in ecology. Disagreements between scholars, as evidenced in the Bulletin of the Ecological Society of America and other journals, of the exact characteristics of invasive species have proven as much. A paper in Diversity and Distributions suggests considering whether or not a species is ‘invasive’ on a case-by-case basis. The following quote outlines how rhetoric can be beneficial in science.

“Current science communication training does the important work of helping scientists understand and practice diverse ways of delivering their messages through storytelling, message framing, on‐camera confidence, and mixed media. But rhetoric can expand the horizon of that training by focusing on how to connect with audiences to prompt identification and action, and inspire critical attention to science.” – Why Rhetoric Matters for Ecology

people inside stadium
Photo by Teddy on

One might begin to wonder, are humans an invasive species? According to science writer Sarah Zielinski, we meet many of the criteria, except for one: We are native to every continent, thus we can’t be invasive when we have always been such a widespread species. It’s an interesting take, but I would say that even if humans once inhabited every continent, those exact populations and their origins have definitely changed over time. One voice in the ‘what is invasive’ debate suggests that a non-native species becomes native once its genetics diverge from the original species. Of course, genetics are different from person to person, so this theory also needs to be fleshed out more.

Thanks so much for reading. I had a fun time crafting this post and got to learn about non-native species that aren’t necessarily harming the environment! Let me know what you think about humans as invasive species in the comments, or anything you’d like to add to the discussion on scientific rhetoric. Have a great day, Jess 🙂

9 responses to “Maybe All Invasive Species Aren’t Terrible?”

  1. Interesting. It reminds me of how mint has taken over my garden yet provides a wonderful herbal tea in the winter!

    Liked by 1 person

    1. Right? A management strategy: drink more tea! and drink it faster than it grows 🙂


  2. Great post. I heard a lecture by a scientist at the Virginia Institute of Marine Science who stated some of the same things… and singled out Phragmites Australis and the benefits of the plant. Yes, I agree about people… 😒

    Liked by 2 people

    1. Thanks for reading, Annie. Seems like ecologists are starting to come to a consensus on what terms to use!

      Liked by 1 person

  3. I read that invasive species are often really “unwanted” species. Evolution is a dynamic process. Species movement and alterations could be seen as part of an ongoing process of change. Biology isn’t static after all, why would we think species location should be.

    Liked by 2 people

    1. That’s so true! Thanks for your thoughts, Cindy.


  4. I live in the UK where there are a number of invasive species. It is now the law that if you take an injured grey squirrel ( invasive from the US) or injured muntjac deer ( introduced from China) to the RSPCA ( Royal society for the prevention of cruelty to animals) for treatment, they are not allowed to be released back into the wild, in fact they have to be put down.
    It’s very sad, though a little understandable in the case of Grey Squirrels especially. The UK has its own native red squirrels which only survive in small pockets round the country , they have effectively been almost killed off by the bigger Grey’s who carry a disease that if caught by reds is fatal. I live in an area where there are no reds and lots of Grey’s. To many people these days the Grey’s are as much part of our wildlife as our much rarer native reds, many people have never seen a red squirrel. I love seeing the Grey’s chase about in my local park. 🙂
    Yet I also own a caravan in Cumbria which is one of the few places in England with a red squirrel population. It is required that any sightings of Grey’s are reported so they can be disposed of. I saw three Grey’s in a red squirrel woodland and I reported it because the reds up there need to be protected.
    In southern England Muntjac deer populations have grown but apparently they cause damage to trees and have caused a road accidents. But this can be said of our native deer too. I have never had the privilege of seeing a muntjac.
    It’s a very controversial subject. 😦

    Liked by 1 person

    1. Thanks for the insight Shazza! I had no idea that the UK is actively trying to get rid of the grey squirrel. Some in the US see them as pests, but they are really important for forest regeneration here. The Eurasian red squirrel looks adorable though.
      Hopefully they find a conservation method that works!


      1. I hope so. It seems a shame that grey squirrels can no longer be treated , especially in non red squirrel habitats.

        Liked by 1 person

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