In 1876, at the Centennial Exposition in Philadelphia, many plants with origins in Japan were displayed, including the Kudzu vine, also known as Pueraria montana. Since then, many farmers discovered the vine’s potential as an erosion prevention method due to their fast-growing roots. In fact, throughout the 1900s, hundreds of men were hired to plant kudzu for erosion control in the southeastern states. Little did they know the large-scale damage kudzu would create.
The southeastern climate was ideal for this invasive species. Known to grow up to 100 feet in a day, the kudzu vine grew up over wildflowers, trees, and just about anything that does not move. In fact, it covers over seven million acres total in the United States today. Kudzu easily outcompetes native grasses and mature trees by preventing them from receiving a substantial amount of sunlight. As these native plants began to die, other organisms in the ecosystem were affected by the cascade effect of the ecosystem, posing a threat to biodiversity. Moreover, because so few herbivores in the region preyed on kudzu, kudzu had the freedom to rapidly grow its population.
So what can we do about it? Dr. James H. Miller from Auburn University wrote a “Kudzu Eradication and Management” paper in 2008 to present several options for controlling the spread of kudzu. He states that no matter what type of solution is used, whether it’s using herbicides, animal grazing, or prescribed burning methods, every kudzu plant in a patch must be entirely eliminated, or else prior investments will be useless.
Kudzu is difficult to manage because they contain rhizomes (underground runners) that lead to the spread of the plant. Containment of the kudzu requires that these underground runners cut completely. Miller says that “the ability for kudzu to spread increases as the plants age because their roots grow larger with time”. Additionally, kudzu can be weakened with mowing and herbicide application, preventing its rapid spread. Miller also describes that cattle grazing has shown the most success in eradicating the kudzu in terms of grazing.
Now let’s look at the big picture. To prevent the spread of invasive species, the most effective solution is to avoid the spread of alien species. During the past several centuries, humans have frequently moved animals, plants, and pathogens around the world, both accidentally and intentionally. For example, the spread of rats from shipping containers led to a high rate of extinction in ground-nesting birds in places such as Hawaii because the rats ate the eggs from the ground nests. Also, some exotic plants and animals are intentionally sold in greenhouses or even sold as pets.
Not all alien species are a threat to biodiversity, and many alien species have no negative effect on native species. However, in other cases, alien species spread rapidly and cause harm to native species, becoming invasive species. It is common for alien species to be invasive because they often do not have any natural enemies in their new regions. This is exactly why the kudzu was able to spread so successfully in such a short period of time in the United States. They pose a threat to biodiversity because they can easily outcompete native species.
As a result of invasive species, we often spend years and decades trying to eradicate invasive species to protect our ecosystems. In fact, many states in the U.S. are still trying to find a way to effectively eradicate kudzu, with some methods requiring ten years of repeated application of herbicides to finally kill a kudzu patch. Even in just two or three years, entire forests could be dominated by invasive species like the kudzu, lowering ecosystem biodiversity and productivity.
The USA has experienced invasions by over 4000 plant species and 2300 animal species