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Invasive Species & Pests

Invasive species are those that are non-native to an area and tend to spread to a degree that causes harm to the environment, local species, or human interests. These problem species have popped up in Pennsylvania over the years, primarily through travel and commerce that displaces them from their native ecosystem. If enough individuals of a species are present to form a breeding population, they can become an invasive species. This has come about from people using exotic plants as decorations, releasing hazardous pets to the wild when they can no longer care for them, and pests that hitch rides in imported foods. Once a new species is introduced, it can become very difficult to get rid of, or even to control. Local plants and animals get choked out by foreign competitors, forests get eaten away by pests, and croplands and pastures become less productive. We must control these species and the effects they cause, and prevent future invasive threats from occurring if we wish to preserve Pennsylvania’s local beauty, wildlife, and productivity. For more information, refer to the NRCS resource concerns.

Invasive species affect the environment in three major topographic areas:

Forest Cropland Pasture
Forked Oak loosing the battle to kudzu Field of Thistle horses_and_thistles
Kudzu vine taking over a forest Thistle growing in a wheat field Invasive plants near a pasture

When invasive species are mentioned, often the first thought that comes to mind are invasive animals and pests. However, invasive plants pose a more common and varied problem. Invasive plant outbreaks occur nationwide and can become epidemics that span several states. One example of this in Pennsylvania is the Multiflora Rose, which grows densely and chokes out native plants, and impedes the nesting habitat of birds.  There are many Invasive species of plants in Pennsylvania, and the Natural Resources Conservation Service (NRCS) implements several programs to encourage and aid in their control. Part of this control is the restoration of native plant communities, so that Invasive species do not re-emerge after being removed from an area. You can find information for financial aid here, and a full list of invasive plants of Pennsylvania here.

Noxious plants, also known as noxious weeds, differ from invasive plants in that they are determined to be injurious to public health, crops, livestock, agricultural land, and other properties. Noxious plant species are fewer in number than invasive plants as a whole, but each poses a greater threat. A full list of noxious weeds in Pennsylvania can be found here.

Noxious and Invasive plants typically reproduce via seed, root, or shoot. The most common invasive plant species are those which reproduce very quickly via root or shoot, or a combination of all three. Those species which reproduce by seed, like the Giant Hogweed, produce large numbers of seeds that germinate quickly. Invasive plant species are typically opportunists, taking over disturbed ground areas and preventing native plants from becoming established. However, some are capable of intruding on established native populations and choking them out. Commonly these are climbing plants such as the mile-a-minute and Kudzu vines.

Invasive species are often those that were grown for ornamental reasons but escape cultivation into the wild. For this reason, the NRCS encourages landowners to grow native plants and avoid known problem ornaments such as the Japanese Honeysuckle and the Multiflora Rose. Invasive plants are also often spread unintentionally by hitching a ride on people or vehicles. Seeds can be dislodged from the tread of boots and tires and spores can be left on the hulls of boats.

The Department of Conservation and Natural Resources (DCNR) offers guidelines to limit the spread of invasive species, under the "Characteristics & Impacts" tab header of their invasive plants webpage.

Invasive Animals and Pests

Invasive animals are those introduced animal species that pose a threat to America’s native wildlife, habitats, or human populations. These include everything from small pests and aquatic animals to medium-to-large sized animals such as the Feral Hog and Burmese Python. Invasive animal species can be spread and introduced through a number of different ways including the release of exotic pets, accidental shipment alongside produce, and in the case of smaller pests and aquatic animals, hitching a ride in cars or boats. Some examples of invasive pests in Pennsylvania include the Asian Tiger Mosquito, Zebra Mussel, Brown Marmorated Stinkbug, and the Japanese Beetle.

Notably, one of the major invasive animals of Pennsylvania, and the United states as a whole, is the feral hog. In the early 1900’s European boars were introduced to America for hunting sport, these wild hogs bred with escaped domestic pigs to make a smaller, and very aggressive, feral hog. These wild pigs inhabit primarily the southern United States and California, but some pockets appear as far north as New York. These pigs can further breed with escaped pigs from domestic farms to contribute to their overall population. For more information on feral hogs and invasive animals, you can visit the USDA Animal and Plant Health Inspection Service (APHIS) website.

Overview of PA NRCS Activities to Address Invasive Species

NRCS helps producers to tackle invasive species problems in four major ways:

  • Financial assistance to manage invasive species and pests;
  • Conservation initiatives that work at a landscape scale to address natural resource concerns, including invasive species;
  • Conservation Innovation Grants with partner entities to support development and implementation of innovative approaches and strategies to address invasive species;
  • Plant Materials Center research geared toward invasive species management and restoring areas where invasive species have been removed.

Conservation Initiatives

The NRCS has implemented a broad spectrum of Conservation Initiatives since January of 2009. These initiatives enable NRCS to more effectively address priority natural resource concerns by delivering systems of practices, primarily to the most vulnerable lands within geographic focus areas.  Several initiatives address invasive species concerns either as a primary concern or through a broader effort to restore wildlife habitat and ecosystems.

  • Golden Winged Warbler: This species of warbler is of concern for its steep decline in population due primarily to habitat loss. The Golden Winged Warbler requires low brush and young forest habitats that the Appalachian region is well suited for providing. Individual programs exist for this and the Cerulean warbler that can provide incentives for conservation.
  • Cerulean Warbler: Similar to the Golden Winged Warbler, this species of warbler requires established broken canopy forests, usually oak, and steep slopes for nesting. Incentive programs are available for private and non-industrial land owners to maintain and increase habitat for these and other species of warbler and migratory songbird.
  • Bog Turtle: America’s smallest turtle, this is a threatened species that lives in open, sunny, spring fed wetlands. The preservation of the Bog Turtle is of particular concern, for the presence of Bog Turtles is an indicator of a wetlands health and function. They are threatened by habitat loss and fragmentation.
  • Forestry: Forests are a major part of Pennsylvania’s structure, our state name actually means Penn’s woods. Naturally, most wildlife in Pennsylvania relies on this resource for food, habitat, and breeding grounds. The Healthy Forests Reserve Program (HFRP) provides programs to help landowners maintain Pennsylvania’s forests in their natural and healthy state for local wildlife.
  • Riparian areas: A second important aspect of Pennsylvania’s environment, our rivers and streams trace their way through several different land ownerships. Therefore, it is important for as many land owners as possible to maintain healthy buffers around riparian areas. A riparian buffer is a strip of trees along each side of a stream or river that stabilizes the banks and catches runoff sediment. These Riparian buffers make streams a more favorable habitat for Pennsylvania’s fish, waterfowl, and amphibian wildlife. The Environmental Quality Incentives program (EQIP) provides incentives for land owners to plant and maintain riparian buffers. 

Conservation Innovation Grants

Conservation Innovation Grants (CIG) fund innovative conservation approaches and technologies to accelerate technology transfer and adoption of promising technologies and approaches to address some of the Nation's most pressing natural resource concerns. Since 2004, NRCS has funded 8 CIG projects in 7 states, totaling $1.9 million, to promote management of invasive species. Projects have ranged from control of plant species in wetlands, pastures, and rangelands to utilizing invasive plant species as a source for biofuel.

Plant Materials Centers

Plant Materials Center (PMCs) in many areas of the country are directly involved in research and education efforts for the detection, control, and management of invasive species. There are no Pennsylvania based PMCs, but the different counties in Pennsylvania are covered by the Big Flats and Beltsville PMCs. PMCs find vegetative solutions to reduce soil erosion, increase cropland soil health and productivity, improve water quality, produce forage and biomass, improve air quality, improve wildlife habitat, restore wetlands, protect streambank and riparian areas, and stabilize coastal areas.

Other Resources

The USDA Agricultural Research Service (ARS) is one of the world's premier scientific organizations. Its nationally-coordinated research solves problems that affect American agriculture. For ARS locations in Pennsylvania and the north east, see their website here.

Points of Contact:

Jim Gillis
State Biologist

Peter Hoagland
State Forester

Susan Parry
State Grassland Conservationist

Mark Goodson
State Agronomist

Last updated:  May 24, 2021