 |
Invasive Species in the Northeastern United StatesDavid Fuller |
|
Invasive Species in the Northeastern United StatesDavid Fuller |
Invasive species are non-native (adventitious) species that are capable of moving aggressively into a habitat and monopolizing resources such as light, nutrients, water, and space to the detriment of other species.
For a species to be designated as “INVASIVE,” the species must:
In other words, a typical harmful invasive plant
1. Norway maple (Acer platanoides)
A tree occurring in upland and wetland habitats, and especially common in woodlands with colluvial soils. It grows in full sun to full shade. Norway Maples can form dense stands and out compete native vegetation, including sugar maples. Acer platanoides is able to shade out native understory vegetation - for example, spring ephemerals - and eventually out compete native tree species in the forest canopy. Thus, it can reduce native species diversity and change the structure of forest habitats. They are dispersed by water, wind and vehicles.
2. Japanese barberry (Berberis thunbergii)
A shrub occuring in open and wooded uplands and wetlands. Japanese barberry grows in full sun to full shade. Berberis thunbergii forms dense stands in a variety habitats ranging from closed canopy forests, to woodlands, wetlands, pastures, meadows and wasteland. It is readily dispersed by birds, which can bring the seeds many meters away from the parent plants. Though the exact effect on native flora is not determined, it could prove a great threat to native species. This threat is such that the plant is illegal for sale in Canada.
3. Oriental Bittersweet (Celastrus orbiculatus)
A perennial vine occuring in uplands that grows in full sun to partial shade. C. orbiculatus destroys native plants by overgrowing them. Shading by the vigorous growth of the vine, and girdling of plants causes major damage. Mechanical damage of trees and other plants is caused by the additional weight added onto the branches - causing the branches to break. Another threat is the possibility of it displacing American bittersweet (C. scandens). C. scandens does not exhibit this aggressive nature, but it can hybridize with C. orbiculatus. Another way in which C. orbiculatus is dispersed is through its use of its fruits for wreathes and floral arrangements in the fall. Oftentimes, after the plant is used, it thrown away and can make its way out into the natural landscape.
4. Autumn-olive (Elaeagnus umbellata)
A shrub occurring in uplands that grows in full sun. Once Elaeagnus umbellata is introduced to a region, it seems only a matter of time before it spreads due to the ability of the plant to produce up to 80lbs. of fruit in a season. Birds (especially starlings) readily eat the fruit in the fall and spread it for long distances. This easy dispersal is what has allowed the plant to spread throughout New England. Elaeagnus umbellata suppresses the growth of other plants by creating shade. It is a good competitor because of its ability to fix nitrogen. If it is cut, it resprouts abundantly. Even burning does not rid the area of this plant, because it still resprouts from the stump. It is aggressive in open areas and has the ability to change soil.
5. Burning bush or winged euonymus (Euonymus alatus)
A shrub capable of germinating prolifically in many different habitats. It grows in full sun to full shade. Since birds disperse the seeds of this plant, it has spread extensively from where it was originally planted. These plants have been observed in dense thickets, threatening native plants by crowding and shading. Often, below the plant is a seed shadow where literally hundreds of seedlings can be found. It threatens a variety of habitats such as forests, coastal scrublands, fields and prairies. This plant continues to be used as an ornamental, thus continuing its spread into the environment.
6. European buckthorn (also known as glossy or common buckthorn) (Frangula Alnus, formerly known as Rhamnus frangula)
A shrub or tree in upland, wetland, and coastal habitats which grows in full sun to full
shade. Rhamnus cathartica has the ability to form dense thickets under which native vegetation cannot survive due to shading and crowding. Many types of birds, as well as small mammals, eat its fruit, easily dispersing it over long distances. A threat to agriculture from Rhamnus cathartica is that it is an alternative host for the crown rust of oats. This rust has a major effect on the yield and quality of the crop. Even after Rhamnus cathartica is cut or burned, it still regenerates.
7. Yellow iris (Iris pseudacorus)
A perennial herb occurring in wetland habitats, primarily in flood plains. Yellow iris grows in full sun to partial shade and out-competes native plant communities. Iris pseudacorus forms large clonal populations that displace native species. The rhizomes of this plant are able to rather heavy droughts. Both the rhizomes and seeds of this plant can be transported downstream allowing for further spread. Even if the wetland area that this plant lives in burns, the seeds will germinate in the now disturbed habitat. In its native habitat, this plant is not widely grazed because of the glycosides it contains, making it poisonous to grazing animals. No birds are known to disperse the seeds of this plant. Iris pseudacorus is still sold and used for water gardens. Caution should be used if pulling out this plant, for it can cause skin irritation.
8. Amur, Morrow's, Bell 's, tatarian, and other shrub honeysuckles (Lonicera maackii, L. morrowii, L. tatarica, L. x bella)
A shrub occurring in upland, wetland, and coastal habitats which grows in full sun to full shade. These honeysuckles are a confusing hybrid complex of nonnative honeysuckles commonly planted and escaping from cultivation via bird dispersal. These honeysuckles can form thickets that prevent other native plants from being established. It is easily spread by birds because of its persistent fruits that ripen in midsummer.
9. Japanese honeysuckle (Lonicera japonica)
A perennial vine occurring in upland, wetland, and coastal habitats. It grows in full sun to
full shade. Lonicera japonica is an extremely vigorous grower and can cover trees and understory shrubs. The weight of the vines can help to bring down trees. This plant not only competes aboveground, but below as well. Due to its dominance of the understory, native tree seedlings and herbaceous plants are unable to grow. The leaves are semi-evergreen to evergreen, allowing them to photosynthesize much later than native species, giving them a competitive edge. In the south, this plant is a major problem. As it gets further north, it can still form large stands, but appears to be limited to some extent by the cold. It appears to be more common near the coast. It produces many seeds that are
dispersed by birds.
10. Purple loosestrife (Lythrum salicaria)
A perennial herb or subshrub occurring in upland and wetland habitats. Purple loosestrife grows in full sun to partial shade. This plant has the ability to completely dominate a wetland setting, forming a vast, monotypic stand. These stands prevent the establishment of native wetland plants. It also can have an effect on native wildlife that may not be able to use the plants as effectively for food or cover. By forming these dense stands, Lythrum salicaria can clog waterways causing problems for both commercial and recreational uses of these areas. Lythrum salicaria can produce up to 2.5 million seeds per plant, and forms a seed bank that can last for years - even if the plants are eradicated from an area. This plant can hybridize with native loosestrife, L. alatum. With repeated hybridizations, it is possible that the gene pool for L. alatum could be depleted.
11. Japanese knotweed; Japanese bamboo (Polygonum cuspidatum, Fallopia japonica and its varieties)
A perennial herbaceous subshrub or shrub occurring in upland, wetland, and coastal habitats. It grows in full sun to full shade, but is hardier in full sun. It spreads vegetatively and by seed to form dense thickets. Japanese knotweed reduces biodiversity through out-shading native vegetation and is a serious threat to many natural habitats, especially watercourses and wetlands.
12. Multiflora rose (Rosa multiflora)
A perennial vine or shrub occurring in upland, wetland and coastal habitats. It grows in full sun to full shade to form impenetrable thorny thickets that can overwhelm other vegetation. Rosa multiflora can be found all across the country because of its ability to endure a wide range of edaphic and environmental conditions. Rosa multiflora rapidly outcompetes surrounding vegetation, takes over pastures, and lowers crop yields. It forms dense, impenetrable thickets. The canes, if in contact with soil will send up shoots. A single plant can produce 500,000 or more seeds. These seeds can remain viable for 10-20 years in the seed bank. Rosa multiflora's hips are dispersed by birds, especially the mocklingbird, cedar waxwing and American robin.