Part of the mission of the Lake Champlain Land Trust is to save the lake's natural communities by permanently preserving significant islands, shoreline areas, and adjacent lands. We are particularly sensitive to the protection of endangered species habitat. Saving natural communities involves protecting them from invasive plants and animals that can quickly displace native and endangered species. Invasive species are most prevalent on disturbed tracts of land and lake. Protecting sections of the lake helps to check the spread of these opportunistic species.
What is an Invasive Species?
People have been moving plants, intentionally or accidentally, from one habitat to another over the course of human history. In most cases, introduced or exotic species are not a threat to new habitats. If the new plants have natural predators in the new habitat they do not significantly change the balance of the ecosystem. On the other hand invasive species are plants or animals that lack predators in their new habitat and have an aggressive growth pattern. When the ecosystem cannot keep a plant’s population within a manageable range, the balance of that ecosystem is tipped, causing the rest of the native species to suffer, decline or become extinct. The purple loosestrife, for example, hails from Europe where many insects feast on it, keeping its population in check. In this country there are no bugs or animals that feed on it or kill it, and so it spreads several million seeds every summer. Additionally, it will re-grow from a cutting, making its removal from an area very tricky.
Most prevalent Invasive Species in the Lake Champlain Basin:
Native Plant: A species that reaches its location without assistance from humans.
Exotic Plant: a plant that been introduced to an environment beyond its original geographic range
Invasive Species: A non-native species that is capable of moving into a habitat and monopolizing resources such as light, nutrients, water, and space to the detriment of other species. ( New England Wildflower Society)
Ecosystem: An ecological community together with its environment, functioning as a unit of interrelated organisms.
Click here for a printable invasive species factsheet!
What invasive species are most prevalent in the Champlain Basin?
Honeysuckle: Tartarian, Morrow, and Belle’s Honeysuckle (Lonicera spp.) are all types of invasive honeysuckle that live in Vermont. Reaching heights of anywhere from one to 16 feet, this creeping vine or thicket-creating shrub strangles trees and shades out much of what is below it. The plant retains its leaves long into the fall giving it an advantage over native plants. Tartarian honeysuckle is native to central and eastern Russia, Morrow honeysuckle is native to Japan.
Buckthorn: A deciduous shrub or small tree, with oval shaped leaves with teeth lining their edges. The flowers are a greenish yellow. It has both glossy and dull leaved varieties (common and glossy buckthorn). Buckthorn lives in open, wooded upland. Common buckthorn is native to Europe, but grows in Asia. Glossy buckthorn is native to North Africa, Asia, and Europe. The buckthorn reproduces often and has an extended growing season, and it re-sprouts with ease. The shrub creates dense thickets, able to shade out many other plants. They most easily infest open areas.
Wild Parsnip: A relatively recent inhabitant of Vermont, wild parsnip (Pastinaca sativa) can be found along roadsides and in fields and pastures. This 3-5 foot tall and lanky plant has a yellow compound umbel, or umbrella-shaped flower that resembles queen anne's lace. Unlike queen anne's lace, wild parsnip harbors a secret that defies its otherwise pleasant appearance. The plant contains chemicals called furanocoumarins which are light sensitive. This can cause sunburns, blisters or a rash when skin is exposed to the chemicals on a sunny day. Please be cautious if you encounter wild parsnip on your travels.
Zebra mussels: A small, thumbnail sized, black and white striped, freshwater mollusk hailing from the Caspian and Black Sea regions of Eurasia. They were discovered in Lake Champlain in 1993, thought to have arrived via the Great Lakes in the ballast tanks of boats and ships. Zebra mussels cause damage on many fronts. They are known to attach en masse to residential, municipal, and industrial water intake pipes, ruin boat hulls and engines, and carpet rocks in the water and on the shore. The mussels are decimating other native mussels by attaching to their shells, making it impossible for the native mussel to open its shell to feed or breathe. As they eat large numbers of plankton in the water, normally eaten by other members of the Lake Champlain food chain, the organisms in the food chain above them become affected. Watch out for zebra mussels where you swim, as they are very sharp and can easily cut the skin.
Eurasian watermilfoil: First discovered in Lake Champlain in 1962, Eurasian water milfoil is a seaweed-like freshwater plant. It spreads by breaking apart and re-growing, making the job of containing it very difficult. Animals as well as people can easily spread this plant all over the lake and into neighboring lakes.
Purple loosestrife: A five-petaled purple plant native to Europe, purple loosestrife can be found in the wetlands of Lake Champlain. Once it enters a wetland, the loosestrife takes over, choking out whatever native plants are living there. By producing millions of seeds in one summer, as well as having the ability to produce roots out of stem shoots, it can easily take over its habitat. Once it is established, the wildlife that call the wetland home are pushed out as well, no longer having native plants as their shelter. Not much can feed off of this plant, so it does little to contribute to the local ecosystem.
Water chestnut: Found in the 1940’s, water chestnut displaces other plants, provides little nutritional value to fauna, and creates thick mats that transform a habitat. Luckily, the infestation has limited itself to the Southern half of Lake Champlain.
For a printable factsheet of the invasive species listed above, click here.
How did they get here anyway?
60% of invasive species introductions have arisen from horticultural activity (arboretums, botanic gardens, gardeners) introducing new species to an area. Conservation activities by various governmental agencies are responsible for about 30% of invasive plants as new species have been introduced to an area for screening, windbreak, and erosion control, but also to supply food and cover for wildlife. Accidental introductions are responsible for the remaining 10%. For example, purple loosestrife was first brought to the U.S. in the hold of a ship via ballast water, as were zebra mussels.
Some invasive species are in fact native to certain regions of North America where they are not problematic. It is when they get introduced into a new region where they have no competition that they become invasive.
Why not just let nature take its course?
Why is it important to protect native species? If we let nature take its course, an invasive plant species can significantly disrupt and alter long established habitats. Without predators or plant competition the invasive species reproduces at aggressive rates, out-competing native plants for sunlight, nutrients and space and out competing native animals or fish for food. As the native populations decrease or become extinct, the genetic pool within the ecosystem is reduced. Wildlife populations within the ecosystem can find themselves without an adequate food source. Smaller animal that depend on plants for food will decline in numbers. The larger animals who depend on the smaller animals for food are then without an adequate food supply and so on up the food chain. Additionally, a diverse selection of native plants and animals keep an ecosystem more resistant to weather disasters and climate change as there is a wider genetic pool of plants and animals to adapt to changing conditions.
Are steps being taken to eliminate or control these invasive species?
Honeysuckle: The best method for honeysuckle is prevention. Clearing small infestation by hand works well, while herbicides or burning are required for larger infestations.
Buckthorn: Many management techniques have been tried in order to control this species, including cutting, mowing, girdling, excavation, and burning.
Wild Parsnip: Methods of removal include hand pulling or cutting the plant near the base (in either case be sure to wear gloves and cover your skin!). Because wild parsnip is a biennial, it is possible to reduce the seed bank with vigilant cutting before seeds form and drop over the span of several years.
Zebra mussels: There is little anyone can do about this problem, save trying to stop the spread of the animals. They are being closely monitored by the Lake Champlain Basin Program and Vermont Department of Environmental Conservation organizations around the Lake. Read more about the Lake Champlain Basin Program’s monitoring of the species at http://www.lcbp.org/zmmonitoring.htm.
Eurasian watermilfoil: Attempts at containing this aquatic plant include mechanical harvesting (much like an underwater lawnmower), hydroraking, building bottom barriers, lake level drawdown, fragment barriers, hand pulling, and biological control via a species of aquatic weevil. It is almost impossible to contain this plant as it can spread through human activity, such as boating, or through animals breaking off stems and carrying them elsewhere.
Water chestnut: The main methods used to deal with this plant are hand pulling and mechanical harvesting.
Purple loosestrife: Many management ideas have been tried including burning, pesticides, and pulling the plant by hand. These have worked to some extent, but only in small, young populations. A better solution seems to be introducing the insects that naturally control the plant in Europe, to the wetlands in Vermont. After years of rigorous testing to ensure that these non-native leaf-eating beetles (Galerucella spp.) would not harm native plants or agricultural crops, they have been put to work, controlling the loosestrife population quite effectively.
How can I as an individual help?
If you are a boat owner, make sure whenever you move your boat from one body of water to the other that it is free of zebra mussels, one of the most dangerous and invasive of all the species. The larva stage of Zebra Mussels is microscopic in size so you cannot necessarily see the enemy here. Clean your boat off when it has come in contact with infested bodies of water, and give it a good look over. Throw any zebra mussels you find in the trash. Drain all water from the boat, including the bilge, live well, and engine cooling system. Dry the boat and trailer in the sun for at least five days, or if you use your boat sooner, rinse off the boat, trailer, anchor, anchor line, bumpers, engine, etc. with hot water or at a car wash. If you're going to reuse your bait, please clean it thoroughly beforehand.
When swimming or boating in an area infested with Eurasian water milfoil, try not to break parts off the plant—this is how the plant spreads.
Learn how to identify invasive species and keep your yard free of them.
Other Invasive Species Resources on the Internet:
InvasiveSpecies. gov - A Gateway to Federal and State Invasive Species Activities and Programs. Has good profiles for each invasive species. (http://www.invasivespecies.gov/profiles/main.shtml#aqplants)
Invasive.org - Invasive and Exotic Species of North America (http://www.invasive.org/)
New England Wildflower Society - Invasive plants (http://www.newfs.org/conserve/invasive.htm)
Zebra Mussel Fact Sheet - Lake Champlain Basin Program