The Silent Invasion
We've been invaded,
but there are no armies, no soldiers. This is a silent invasion.
The aggressors are invasive plants that are silently creeping
over vast expanses of natural areas, wreaking havoc on local ecosystems.
The majority of these invasive plants are also non-native. Plants
native to North America are generally recognized as those occurring
on the continent prior to European settlement. Non-native plants
are species that have been introduced to an area by humans from
other continents, states, ecosystems and habitats. Many non-native
plants have great economic value for agriculture, forestry, horticulture
and other industries and pose little to no threat to our natural
ecosystems. Others have become invasive and pose a serious ecological
Plants are considered invasive if they spread out of control dominating
the local environment and crowding out native plants. Because
they have been introduced into an environment in which they did
not evolve, there are no natural predators, parasites or other
controls to keep these invasive plants in check. Invasive plants
grow fast and mature early in the season and reproduce profusely.
Some invasive vines will actually bring down trees by their sheer
They out-compete native plants for light, water and nutrients
and eliminate entire native plant communities---and they change
the composition of the landscape. The ecological balance of plants,
animals, soil, and water achieved over many thousands of years
is destroyed. As native plants are displaced, animal populations
that rely on the plants for food and shelter also decline. When
invasive plants take over wetlands, forests or meadows, we lose
the native plants and the habitats that local wildlife need.
In the United States, invasive plants already infest more than
100 million acres and continue to increase by 8 to 20 percent
annually. Once established, invasive plants require enormous amounts
of time, labor and money to control or eliminate. Invasive species
cost the United States an estimated $34.7 billion each year in
control efforts and agricultural losses.
Invasive plants also affect the type of recreational activities
that we can enjoy in natural areas such as boating, bird watching,
fishing and exploring. Some invasives become so thick that it
is impossible to access waterways, forests and other areas.
Estimates indicate that non-native plants infest 4,600 new acres
of federal land each day. Each year, non-natives spread into an
area larger than the state of Delaware. Overall, invasive plants
threaten every aspect of the North American environment including
national wildlife refuges, national parks, recreation areas, wilderness
areas, forests, wetlands and croplands.
Spring has sprung and, like countless other Americans, you're
going to spend some time and money sprucing up and landscaping
your yard. Be careful when choosing plants---you could unknowingly
introduce an invasive plant. Many times homeowners don't know
that a plant in their yard can become a menace in the wild. However,
some common landscape plants found at most nurseries are invasive.
Become familiar with invasive plant species in your area and avoid
planting them. Ask for native-plant alternatives at your nursery.
If you already have invasive plants on your property, consider
removing them and replacing them with native species. Here are
a few troublesome plants to avoid, followed by suggested native
Purple loosestrife (Lythrum salicaria); native alternatives:
blazing star (Liatris spicata), cardinal flower (Lobelia
cardinalis), obedient plant (Physostegia virginiana).
Chinese wisteria (Wisteria sinensis) and Japanese wisteria
(Wisteria floribunda); native alternatives: American
wisteria (Wisteria fructescens), trumpet creeper (Campsis
radicans) trumpet honeysuckle (Lonicera sempervirens).
Bradford pear (Pyrus calleryana 'Bradford'); native alternatives:
redbud (Cercis canadensis), serviceberry (Amelanchier canadensis),
southern arrowwood (Viburnum dentatum).
The National Park Service and U.S. Fish and Wildlife Service have
put together the publication entitled "Plant Invaders of Mid-Atlantic
Natural Areas." The color guide describes common invasive plants
and alternative native plants to use instead. To receive a copy,
contact U.S. Fish and Wildlife Service, Chesapeake Bay Field Office
at (410) 573-4500 or download a copy from www.nps.gov/plants/alien/pubs/midatlantic.
For more information, visit the USFWS, Chesapeake Bay Field Office's
BayScapes website at www.fws.gov/r5cbfo/Bayscapes.htm.
Kathy Reshetiloff is employed by the U.S. Fish and Wildlife Service, U. S. Department of the Interior.