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Invasive Plants Move North

Fall foliage is the veritable trademark of the Northeast. Families flock from around the world to take in the natural splendor.

Imagine autumn in New England without its distinctive palette - choked out by a dense labyrinth of invasive vines.

This nightmare may become a reality in the near future if current climate trends continue, increasing the threat of invasive plant species to the Northeast Region.

Invasive plants are non-native to a region, and likely to cause harm to the area’s wildlife and human populations.   The U.S. Fish and Wildlife Service’s Invasive Species Program is committed to preventing the spread of invasive plants and minimizing their impact on native plants and animals.

“The main story,” says Bethany Bradley a Copeland Fellow at Amherst College in Western Massachusetts who has extensively studied invasive plants, “is they are moving north.”

Invasive plants like glossy buckthorn, Japanese barberry, and phragmites, to name a few, are already prevalent in the Northeast.  Other species are relatively new to the northern realms, like Japanese stiltgrass and mile-a-minute vine. Additional species that currently torment the southern states are expected to expand their range north due to a host of environmental factors including increases in temperature and precipitation in northern latitudes.

Bethany Bradley, a scientist who has extensively studies invasive plants, says that "they are moving north."
Bethany Bradley, a scientist who has extensively studies invasive plants, says that "they are moving north."

Introducing additional stressors to an already fragile ecosystem can have a devastating impact on native plants and animals.  Once an invasive plant species becomes ingrained, it crowds out native species that the region’s animals have come to depend on.  

“Invasive vines such as Asiatic bittersweet will grow up trees and prevent the tree from photosynthesizing,” says Cynthia Boettner the coordinator of the Invasive Plant Control Initiative for the Silvio O. Conte National Fish and Wildlife Refuge.  “If the tree dies, it can’t provide nuts and seeds that animals feed on.  Others, such as garlic mustard, can prevent the regeneration of forest tree species. “

The net effect of an invasive plant infestation is nothing less than a fundamental change in the structure and function of a habitat.

Known as “the vine that ate the South”, kudzu, an invasive, fast-growing vine, is pervasive in the southern US.  The vine is of particular concern because it smothers and kills nearby vegetation including trees. So far, frigid winter temperatures have prevented the widespread expansion of kudzu into northern latitudes.  But that could all change.

“Kudzu is not very tolerant of winter frosts,” says Bradley.  “What if it’s two degrees warmer?  Twenty to thirty years from now, if we get enough warm winters, what happens to the New England forest?”

Climate models based on current climate trends predict an increasing range of risk for kudzu (http://www.springerlink.com/content/dm78817510323m04/fulltext.pdf).  In one hundred years, according to the models, kudzu and other invasive plants may have a stranglehold on the beloved New England forests.

The impact of invasive plants goes beyond the ecological well being of forests and wildlife.

“Invasive plants have huge economic consequences,” says Bradley.  “We’re talking billions of dollars a year in the US alone in lost agriculture and human time and effort trying to control and manage the consequences.”

Controlling the spread of invasive plants and mitigating their impact on habitats is an integral part of the Conte refuge and the US Fish and Wildlife Service’s mission.  For invasive plants, early detection and rapid response (EDRR) are paramount.

“The silent invader,” says Andrew French describing invasive plants.  French is the project leader at the Conte refuge, located along the Connecticut River, stretching from the Canadian border to the Long Island Sound.  His team has engaged in a protracted battle in recent years to manage the spread of invasive plants (see sidebar).

The Conte refuge and the Service have partnered with the University of Connecticut and the New England Wild Flower Society to establish the Invasive Plant Atlas of New England (IPANE), supported by a grant from the US Department of Agriculture.  A web-based atlas, IPANE catalogs invasive plants in the region based on field reports from a network of professionals and trained volunteers.  The website provides a wealth of information about invasive plants in the region.

Kudzu, which can grow up to a foot per day, has recently been found in Marblehead, Mass and as far north as Canada.  With the range of invasive plants, like kudzu, expected to increase in the coming years, the Conte Refuge and the Service are integrating climate change into early detection and management plans – the key to controlling the threat.

Because the refuge includes significant variations in latitude and elevation, says French, it is particularly well suited to monitor and react to changes in the regional climate and the related spread of invasive plants.  To this end, French has submitted a grant proposal that would establish a network of “Cooperative Weed Management Areas” to better monitor, track, and manage invasive species in the watershed.

Story by U.S. Fish and Wildlife Service intern Bill Butcher.


Water Chestnut Eradication Project

Each year, we pull and remove water chestnut plants to help control its spread.
Volunteers and staff pulling water chestnut in canoes

Most of us know water chestnut as the crunchy, potato-like ingredient popular in Asian cuisine.  But an unrelated plant, that happens to share the same name, is the last thing you’d want to find in your stir-fry.

The plant known as water chestnut in North America, an invasive aquatic plant that while technically edible is not consumed in the U.S., has become a significant problem in some of the Northeast’s waterways.  The Conte refuge is trying to prevent it from becoming a problem in the Connecticut River watershed.

Left undisturbed, the plant completely covers the surface of shallow water bodies, displacing native plants and making it impossible to swim, boat, or fish.

As part of a multi-faceted eradication project, the Conte Refuge enlists large numbers of volunteers and cooperators, who spend many hours hand-pulling the plants to clear all the water bodies where it is known to occur in the Ct. River watershed in Connecticut, Massachusetts, and Vermont. 

A few populations are too large and dense for hand-pulling.  A 20-acre infestation at Log Pond Cove in Holyoke, Massachusetts is controlled each year - preventing it from setting seed with the use of herbicide (after machine harvesting proved ineffective).

Citizens, water department employees, and Service fisheries program staff also inspect many new water bodies to try to discover any new infestations. In 2009, water chestnut was hand-pulled at 33 sites where plants have been pulled in previous years; among those sites, six were found to be essentially clean of the species.  If you are interested in volunteering, please contact cynthia_boettner@fws.gov.

Story by U.S. Fish and Wildlife Service intern Bill Butcher.


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