Invasive Plant and Insect Species in New London, New Hampshire

An invasive plant is a non-native species that invades a region and spreads rapidly. It displaces native plants and is disruptive to the native ecosystem. Invasive insects and fungi also invade a region and spread rapidly. They will attack and distroy trees and other plants.

What is an invasive plant?

A native plant is found in a particular region, ecosystem and habitat without direct or indirect human action. Plants native to our country are generally recognized as those occurring prior to European settlement. Non-native plants occur artificially in locations beyond their known historical natural ranges. Non-native can refer to plants both brought in from other continents or moved by people within the United States.

The most important aspect of a non-native plant is how it responds to a new environment. An invasive plant is one that displays rapid growth, allowing it to spread over large areas. Free from natural controls present in our area such as herbivores and disease, invasive plants experience rapid and unrestricted growth in new areas. These invasives share features such as strong vegetative growth, abundant seed production, long-lived seeds, and rapid maturation.

Invasive plants are one of the greatest threats to our natural ecosystem by disrupting the local ecology, and by displacing native plant and animal species. Aggressive invaders reduce the amount of light, water, nutrients, and space available for native species, as well as altering the hydrological patterns, soil chemistry and moisture-holding capacity of the ground. Garlic mustard has been found to contain compounds lethal to a native butterfly species.

In 1998 it was estimated that the National Park Service and the Fish and Wildlife Service spent 2 and 10 million dollars, respectively, on controlling invasive plants. Each year economic losses measured in billions of dollars are sustained by agriculture, forestry, range lands and roadway management. Our national parks and forests were losing 4,600 acres a day to invasive plants.

Our native fauna depends on native plants for food and shelter. While some have a varied diet and feed on a wide number of plant species, others are highly specialized and are restricted to feeding on several or a single plant (host) species. Caterpillars of the monarch butterfly feed primarily on milkweed that contain special chemicals. The invaders do not supply the necessary nutrition for wildlife as do our natives. The fruits of native plants such as blueberry, holly and viburnum are high in fats and lipids; sources of long-term energy while the fruits of invasive plants are often high in sugar.

The best way to reduce plant invasion is to focus on preventing non-native species introductions, managing existing infestations, minimizing disturbance to forests, wetlands, barrens and other natural communities, and learning to work with, rather than against, “Mother Nature.”.

General information on invasives in the United States may be found at USDA.. Additional information for New Hampshire is available in the Invasive Plant Atlas of New England, the Guide to Invasive Upland Plant Species in New Hampshire, and Aquatic Plants & Algae of New Hampshire's Lakes and Ponds.

Terrestrial Invasive Plants in New London

New Hampshire produces periodically a list of prohibited invasive plants that cannot be sold in or transported into the state and a restricted or watch list for non-native plants that are potentially invasive. As of 20 October 2009, there are 27 species on the prohibited list and 26 on the watch list. Some of the plants on the prohibited list were favorites of landscapers because they were robust and easy to grow. The NH Department of Agriculture has provided a recommended list of alternatives for the more popular prohibited plants. Invasive plant identification information is provided in the atlas and guides listed above.

An invasive plants brochure generated by the Environmental Studies program at Colby-Sawyer College describes some of the invasive plants that have been found along the roads in New London. Additional information on plants in New London may be obtained from the on-line virtual herbarium at Colby-Sawyer College.

Several invasive plant infestations are now found along roads and on town land in New London. They can readily spread to private land and invasive species on private land will readily spread to public land. Control of the invasives that are present is difficult. Herbicides can be used by individuals on their own land on areas outside the shoreline and and stream buffer zones. The town is required to use a licensed contractor to apply herbicides on its public land. The state has similar restrictions but no funds to control invasives along state roads. The NHDOT published a Best Management Practices for Roadside Invasive Plants report in 2008. This report outlines their recommended methods for the control of Japanese Knotweed, Common Reed and other invasives present in our state.

Three invasive plants have widespread occurances in New London, Japanese Knotweed, Common Reed and Burning Bush:

Japanese Knotweed from outlook in Low Plain

Common Reed across from Post Office

Burning Bush in fall red from Sherman Rd.

Burning Bush was declared invasive by New Hampshire in 2007 so it cannot be sold or imported into the state but does not have to be removed by private land owners.

The New London Conservation Commission has done studies on the control of Japanese Knotweed along town roads and is currently involved in a study at the Stump Dump.

For more information on invasive plant in our region visit Invasive Plants in the Upper Valley.

Aquatic Invasive Plants in New London

Exotic invasive aquatic plants pose a potential problem for the lakes in town. Infestations of exotic aquatic species have been recorded by the New Hampshire Department of Environmental Services (NHDES) at 72 lakes and ponds in the state (exotics in New Hampshire) through November 2007. The infestation sites closest to New London are Lake Sunapee in Sunapee and Massasecum Lake in Bradford.

View of a milfoil infestation in Squam Lake (from NHDES: http://www.des.state.nh.us/wmb/exoticspecies/photos.htm)

In a small, shallow lake, a milfoil infestation could severely limit the use of the lake for swimming or fishing.

Milfoil is spread from lake to lake by plant fragments that get caught on boats, motors, boat trailers, fishing tackle or anything else that could snag and hold the fragment. It is spread within a lake by drifting plant fragments created by boat propellers or by cutting the aquatic weeds in an attempt to control them. The lake associations in the Town of New London are actively working to prevent possible infestations by inspecting boats at boat ramps and requesting that any suspicious plant fragments be removed prior to launch. They are also educating the boating public about invasive aquatic plants in person or via signs at the boat ramps.

Periodic plant surveys are made during the boating season to provide early detection of an invasive species while eradication is still possible. NHDES provides information on the exotic aquatic species in New Hampshire to assist in early detection.

Invasive Insects in New Hampshire

The New Hampshire Department of Agriculture includes 16 insects on their prohibited list. The Hemlock Woolly Adelgid is aleady in southern New Hampshire. The Emerald Ash Borer and the Asian Longhorned Beetle are not in New Hampshire as yet but are in nearby states. They can be brought into the state or from place to place within the state in contaminated firewood. The transportation of firewood across state lines and over distances of 50 miles or more within a state is discouraged and, in some states, illegal.

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