Invasives are species that are transported from other regions of the world (either accidently or on purpose) and once they become established can expand rapidly overtaking the native ecosystem. Such species are able to dominate because they often grow faster, earlier, disperse more easily, and have no natural predators. In the interest of preserving a healthy native ecosystem, the refuge is actively managing invasive species to limit their spread. Some examples of invasives that can be found on the refuge include:
Tree of heaven - Tree of heaven was introduced to the U.S. from China in 1784 as a landscape tree. It addition to its rapid growth and dispersal it also suppresses growth of surrounding native trees with chemicals released by its roots.
Japanese Knotweed - Japanese knotweed (pictured top left) was introduced in the late 1800’s as an ornamental plant. It has become one of the worst invasive species in riparian habitats. In early spring a red/purple shoot will appear from the ground and begin to grow long hollow canes. As it develops the leaves will turn green and by early summer it will be full grown up to 12’ tall.
Mile-a-minute - The mile-a-minute weed was accidentally released into the wild from a nursery in the 1930’s. This native of eastern Asia has since spread throughout much of the north-eastern United States. It is easily identifiable by its triangular leaf.
Autumn olive - Autumn olive is an invasive that was introduced into the United States from Japan in 1830 when it was used for vegetation of disturbed soils. It overtakes other species in such areas because it can better survive in poor soil conditions.
Multi-flora rose - Multi-flora rose was introduced from Japan in 1886 as a way to prevent erosion. It was also used as a living fence for livestock because of its dense growing patterns. This thorny shrub will quickly fill in an open field and can impede movement of larger animals.
Kudzu - Kudzu was introduced from Asia in 1876 as an ornamental vine. In 1930 it was introduced into the wild as a tool for erosion control. Kudzu grows very rapidly, up to a foot per day, on average growing up to 60 feet in one season. Its rapid growth covers and shades out native plants and can girdle trees with its large vines.
Asian carp - Asian carp refers to several different species including the Bighead and Silver carp. These species were introduced into the U.S. in the 1970’s as a source of food and as a way to clean aquaculture ponds. Unfortunately, they escaped into local waterways during flooding events, and are now moving up the Ohio River. Currently their presence has been verified as far upstream as Huntington, WV. These invasive species crash the food chain though overconsumption of plankton and algae. These are large fish with an average weight of 30- 40 lbs and a maximum weight of over 100 lbs. They pose a safety hazard to boaters as they become frightened by the sound of motor boats, causing them to jump up out of the water in large numbers.
Zebra mussel - These Caspian Sea natives (pictured top right) entered the Ohio River in the early 1990s, most likely through barge and boat traffic. Zebra mussels are small but they grow in dense colonies which can cover any stationary surface, including rocks, boat docks, and boat hulls. They even attach to live native mussels. This can kill the native mussel as it limits their access to food and oxygen.
For more information on invasive species visit the U.S. Fish and Wildlife Service Invasives Website.