Florida has one of the largest invasive species issues in the country. Our warm climate, active ports, and high international travel make our state a good target for these species to take hold. They represent a threat to the natural ecosystem. Here are the three characteristics used to define either plants or animals that are considered invasive. Based on the definition from the University of Florida, all three must be true for the term to be used correctly.
1. Invasive species are non-native.
Non-native is a relative term. There are plants and animals from south Florida that are non-native to north Florida. Does this mean mangroves are invasive? No, not unless the other two characteristics mentioned here are true. There is no doubt lionfish and beach vitex are non-natives. Lionfish are from the Indo-Pacific region and beach vitex is from the Pacific shorelines of Asia. What about a plant or animal from the Rocky Mountains? Again, like mangroves… they could be.
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Beach Vitex © Krystin Boehnke
2. Invasive species reached this area with the assistance of humans. They did not get here on their own.
All species of animals and plants establish a range determined by the resources they need and the barriers that impede further dispersal – such as a body of water. With invasive species, natural barriers are removed with the aid of humans. We either intentionally or accidentally bring them across barriers. Lionfish could not have made the trip across the open ocean from Indonesia to Florida on their own. Their eggs follow the currents and they require warm conditions where there are reefs, or some other hard habitat, in which to hide and hunt. In this case they were flown here intentionally for the saltwater aquarium trade. Beach vitex is similar. Their seeds can be dispersed by water or by birds, but this plant was brought in from South Korea for landscaping purposes. Mangroves have been found growing in the northern Gulf of Mexico, north of their traditional range. However, most evidence points to a natural dispersal from south Florida – thus we would not call them an invasive species.
3. Invasive species must cause either an environmental or economic harm – maybe both.
To call them invasive, they have to be causing some sort of problem. For example, orange trees are not native to Florida. They are originally from Asia and have dispersed to other continents and eventually to Florida by purposeful action. But orange trees are NOT a problem, being one of the more economically important plants in our state. On the other hand, beach vitex is problematic. The plant grows aggressively on our dunes, competing with native plants and seeds needed for dune stabilization and feeding wildlife. Vitex vines grow over the top of the sand and can grow as much as 20 feet in one month during the summer. This could potentially also impact sea turtle nesting. So, beach vitex is considered an invasive species in Florida.
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Rhizome Of Vitex © Shannon O’Connor