Invasive Plants On Our Roadsides

Melissa Toni, NYSDOT Environmental Protection Specialist

What are Invasive Plants?

Invasive plants are non-native species that outcompete native vegetation, disrupting ecosystems. They are found along most roads in New York State, and are one of the greatest threats to biological diversity and general ecology in the United States. The only larger threat to ecosystem diversity in New York State is the destruction of habitat. Just how common are they? There are more than 130 different species of invasive plants already established in the Finger Lakes region alone.

What do invasive species have to do with roads in particular? Highway and road corridors provide numerous opportunities for the movement of invasive species: seeds can move on vehicles and in the loads they carry; seeds and plants can be moved from site to site during spraying and mowing; seeds can be introduced into the corridor during construction on equipment and in mulch, soil, and sod; and plants already present have a clear open corridor for wind to spread the seeds to other locations along the right-of-way.

Common Examples

Purple loosestrife is one example of an invasive species. It was introduced into gardens as an ornamental plant because of its showy purple flower. The seeds then spread to wetlands near the gardens. After many growing seasons, purple loosestrife is currently found in most large wetland areas in New York State, and in large proportions to native plants. It outcompetes native wetland plants that provide food for waterfowl and other animals that rely on the wetland area. As a result, waterfowl have less to eat during migration and nesting seasons, and the wetland cannot support as many birds.

There are many other species of invasive plants found here. Six of the more problematic, referred to as ‘target plants’ by the Invasive Plant Council of New York State, are Giant Hogweed, Japanese Knotweed, Japanese Stiltgrass, Mile-a-Minute Vine, Pale Swallow-wort, Black Swallow-wort and Water Chestnut.

Control & Management

Invasive species control and management is a significant concern to the Federal Highway Administration (FHWA). There is also an Executive Order which prohibits Federal agencies from authorizing, funding, or carrying out actions that it believes are likely to cause or promote the introduction or spread of invasive species.

Purple Loosetrife

The FHWA encourages construction and landscaping techniques that help to accomplish the intent of the Executive Order and promote environmental stewardship. Methods include minimizing soil disturbance to reduce opportunities for the introduction of invasive species, control of existing areas through mowing or spraying, using more efficient equipment cleaners, and using improved seeding equipment for steep slopes.

Resources

NYSDOT procedures for managing invasive species

The Invasive Plant Council of New York State

The FHWA field guide to common roadside invasive plants

Spring 2009

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This work by the Cornell Local Roads Program (CLRP) is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License.