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what ecological traits do successful invasive species possess?

how do these traits interact to make controlling them difficult? Example in Maryland.....

Public Comments

1. fur
2. There are many examples...for instance, an invasive species has to do one of several things to be successful. It must be able to replace a native species (plant or animal) - grow faster, be more hardy to temperature or climate or environmental changes.. Or it may not have any natural enemies or predators. In the case of plants: An invasive species produces large numbers of new plants each season. It can tolerate many soil types and weather conditions. It can spread easily and efficiently, usually by wind, water, or animals. It grows rapidly, allowing them to displace slower growing plants. It spreads rampantly when they are free of the natural checks and balances found in their native range. For example, some plant species are kept in check by animal grazing or insect activity. If you remove a particular species and plant it around the world in an area where it has no natural checks, it could run rampant. But importantly, an invasive plant has the ability to thrive and spread aggressively outside its natural range. A naturally aggressive plant may be especially invasive when it is introduced to a new habitat. An invasive species that colonizes a new area may gain an ecological edge since the insects, diseases, and foraging animals that naturally keep its growth in check in its native range are not present in its new habitat. Some invasive plants are worse than others. Many invasive plants continue to be admired by gardeners who may not be aware of their weedy nature. Others are recognized as weeds but property owners fail to do their part in preventing their spread. Some do not even become invasive until they are neglected for a long time. Invasive plants are not all equally invasive. Some only colonize small areas and do not do so aggressively. Others may spread and come to dominate large areas in just a few years. For example, look at "Kudzu" grass. Kudzu was introduced to the United States in 1876 at the Centennial Exposition in Philadelphia, Pennsylvania. Countries were invited to build exhibits to celebrate the 100th birthday of the U.S. The Japanese government constructed a beautiful garden filled with plants from their country. The large leaves and sweet-smelling blooms of kudzu captured the imagination of American gardeners who used the plant for ornamental purposes. Florida nursery operators, Charles and Lillie Pleas, discovered that animals would eat the plant and promoted its use for forage in the 1920s. Their Glen Arden Nursery in Chipley sold kudzu plants through the mail. A historical marker there proudly proclaims "Kudzu Developed Here." During the Great Depression of the 1930s, the Soil Conservation Service promoted kudzu for erosion control. Hundreds of young men were given work planting kudzu through the Civilian Conservation Corps. Farmers were paid as much as eight dollars an acre as incentive to plant fields of the vines in the 1940s. Kudzu's most vocal advocate was Channing Cope of Covington, Georgia who promoted use of the vine to control erosion. Cope wrote about kudzu in articles for the Atlanta Journal-Constitution and talked about its virtues frequently on his daily WSB-AM radio program broadcast from his front porch. During the 1940s, he traveled across the southeast starting Kudzu Clubs to honor what he called "the miracle vine." Cope was very disappointed when the U.S. government stopped advocating the use of kudzu in 1953. The problem is that it just grows too well! The climate of the Southeastern U.S. is perfect for kudzu. The vines grow as much as a foot per day during summer months, climbing trees, power poles, and anything else they contact. Under ideal conditions kudzu vines can grow sixty feet each year. While they help prevent erosion, the vines can also destroy valuable forests by preventing trees from getting sunlight. This problem led Dr. James H. Miller of the U.S. Forest Service in Auburn, Alabama to research methods for killing kudzu. In eighteen years of research, he has found that one herbicide actually makes kudzu grow better while many have little effect. Miller recommends repeated herbicide treatments for at least four years, but some kudzu plants may take as long as ten years to kill, even with the most effective herbicides. Since you are asking about Maryland, here is the information right off the Maryland Department of Natural Resources Webpage regarding invasive species: http://www.dnr.state.md.us/wildlife/invintro.asp "Since early colonization of North America, new species have been introduced at an ever increasing rate. These species have arrived through a variety of pathways, including through the ballast of ships, in the packing material of imported goods, and through deliberate import for various uses. While most of these introduced species are beneficial or benign, about 15% become invasive. An invasive species: 1. Shows a tremendous capacity for reproduction and distribution throughout its new home; and, 2. Also has a negative impact on environmental, economic, or public welfare priorities. Many introduced species do not show a propensity to become invasive for several generations; so species we once thought were beneficial, such as grass carp, European starlings, mute swans, and nutria have demonstrated the characteristics of invasiveness long after their original introduction. These and other species are proving difficult to control in their competition against native species for food, shelter, water, or other resources and their impacts on economic interests and human welfare. Without the disease and predators that they contend with in their native lands, the spread of these species can be epic in proportion and the effort to control them can reach billions of dollars. The U.S. Fish and Wildlife Service estimates a potential economic impact of $5 billion in the Great Lakes attributed to impacts of the zebra mussel and attempts to mitigate those impacts. Zebra mussels have virtually eliminated native mussels from the Great Lakes and altered the basic food chain, threatening the availability of microscopic food for native fish. What do we mean by native species? Generally, we mean species of plants and animals that have evolved in the Chesapeake Bay watershed and have developed mutually-sustaining relationships to each other over geologic time. Certainly, some native species can become invasive when habitat is altered and their particular needs are met on a much broader scale. When ecologists talk about the impact of introduced species on native species and habitats, they mean that the introduced species is reproducing and distributing itself so efficiently that it is out competing native species' use of the same habitats. Nature is in a very delicate balance, much altered by humans, and the protection of remaining natural interactions between native species and their habitats are responsibility of local, state, and federal agencies and all citizens. With their highly efficient reproduction and use of new habitats, introduced invasive species can and have quickly eliminated native species from the landscape. In fact, over 45% of species federally listed as endangered, rare, or threatened are being impacted by introduced species in the United States. On Pacific Rim islands, Madagascar off the coast of Africa, Australia, and Puerto Rico, introduced species are wreaking havoc on native species and severely altering their habitats. Introduced invasive species can include creatures such as viruses as well as large mammals and everything in between, including amphibians, reptiles, birds, insects, plants, fish, shellfish, even jelly fish. In Maryland, one of our primary concerns is the impacts of invasive plants on habitats that support rare, native plants and plant communities. These communities include shale barrens, vernal pools, and peat bogs. We are also concerned about: *mute swans (Cygnus olor) *nutria (Myocaster coypus) *zebra mussels (Dreissena polymorpha) *water chestnut (Trapa patens) *phragmites (Phragmites australis) *purple loosestrife (Lythrum salicaria) *wavyleaf basketgrass (Oplismenus hirtellus ssp. undulatifolius) Also, included among species of concern are over 200 introduced species that have viable, wild populations in the Chesapeake Bay watershed, recorded by the Smithsonian Environmental Research Center. "