by Neil Stalter | Zoom Out Mycology
It can be a little weird to look at a plant, insect, or animal and think “I wonder where that came from?” but that can actually be one of the most important questions to ask for environmentalists! Whether a certain species is native to your area or “invasive” meaning that it came from somewhere else, can be fundamentally important to how ecosystems change and evolve over time.
Before we get into that though, it’s important to understand exactly what an “invasive species” is, and why we should care. There are four types of species that are not native to the area in which they live: Introduced, Exotic, Alien, and Invasive species. “Invasive” species are those that are both non-native while also having a negative effect on the ecosystem or economy that they have invaded. Potatoes, for example, are an introduced species that started in South America, and eventually spread to Europe and North America (1), but don’t have a negative effect (can you imagine a world with no French fries?). This means that potatoes are non-native and introduced, but not invasive because they don’t have a negative effect, and instead provide an economic benefit to the places they were introduced. On the other hand, there are a lot of weeds that are invasive species that can prevent us from effectively growing our crops! Species like Giant Hogweed have invaded and can cause major damage for our farmers and gardeners.
What negative effects an Invasive species can have depends a lot on the species in question. Often times, these species that are introduced to a new area, whether by boat, farming, gardening, or by accident, lack any predators in the new areas they find themselves in. Ecosystems need time to evolve to keep all of the species that live in them in check. Wolves have had a lot of time to evolve and hunt deer and buffalo, but they would struggle to hunt as effectively if all of a sudden, elephants took the place of those buffalo they were used to hunting. This is a dramatic example that probably would never happen, but it’s a useful way to describe how these ecosystem dynamics can change when a new species arrives. These invasive species can then take over entire ecosystems unchecked, causing immense damage. In fact, it is estimated that the spread of invasive species has contributed to the decline of 42% of the listed threatened and endangered species, and the damage done by them has cost the US an estimated $120 billion (2). Much of this cost is due to damage to agriculture, but these invasive species can have profound negative effects on ecosystems where the cost is harder to calculate, like lakes. To best describe invasive species and the damage they can do, I’ll tell you about three invasive species that each are very different from each other, but each pose a very significant threat to ecosystems in the US and around the world: Zebra Mussels, Varroa Mites, and the Emerald Ash Borer. Stay tuned until the end of the article for some suggestions about what you can do to help combat this problem and stay educated!
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