Invasive Plants

A before and after photo of the area around Forbes Rock on Culp's Hill where the invasive plant species Japanese Stiltgrass has been removed by park biologists and volunteers.

NPS Photo

In 2024 the park’s natural resource team and a band of volunteers began the process of addressing the infestation of Japanese stiltgrass on Culp’s Hill. The photo above shows the initial steps taken, the physical removal of as much of the invasive plant from around Forbes Rock. Though it may seem as if the area was left stripped of all plant life, the aggressive removal of stiltgrass is the just the first step to give the native and naturalized plants the best opportunity to take back their homes and flourish.

Your continued aid through volunteering with the park is what provides the plants, that should be here, the assistance to come back from utter devastation brought on by invasive species like Japanese stiltgrass.

 

Black-eyed Susan (Rudbeckia hirta)

NPS photo

Native Plants

***These are All Good*** Native plants are species that occur naturally, without human intervention, and arrive in an ecosystem through natural processes like seed dispersal by wind, water, or animals, or through the establishment of new populations from existing ones. National Park Service Management Policies define native species as, “all species that have occurred, now occur, or may occur as a result of natural processes on lands designated as units of the national park system. Native species in a place are evolving in concert with each other.”

 

 

A butterfly drinking nectar from Butterfly Weed (Asclepias tuberosa)

NPS photo

Non-Native Plants

***These are Beneficial, Some are Neutral, and Some Turn Bad*** Non-Native plants are those that have been introduced to an area where they did not naturally exist before. Non-native plants may be introduced intentionally, typically for agricultural of aesthetic purposes, or unintentionally as seed hitchhikers on clothes, vehicles, or other materials. It’s important to note that not all non-native species are considered invasive.

Several intentionally introduced non-native plants can be observed at the park, and include cultivated plants like soybeans, wheat, rye, and domesticated apple trees. These plants provide food and economic and aesthetic value to humans. Cultivated plants occasionally escape their confines and grow freely in natural ecosystems. There are many examples of escaped ornamental plants that now grow in places they weren’t originally planted. Similarly, some unintentionally introduced non-native plants can survive in an introduced habitat.

Sometimes these escaped or unintentionally introduced plants become “naturalized” and persist in a way that’s minimally disruptive to ecosystem function (for example, dandelions are a common non-native lawn weed, but rarely become a serious problem in native ecosystems in this area).

However, some non-native species are capable of rapid growth and spread throughout an ecosystem, resulting in the disruption of natural processes or human wellbeing, and these plants are classified as invasive species.

 

Mile-a-Minute Weed

NPS photo

Invasive Plants

***These are All Bad*** Invasive plants are non-native plant species that cause harm to the environment, the economy, or plant, animal, or human health (NPS Executive Order 13751). Once an invasive species has established itself, removing it or eradicating it can be extremely difficult, requiring large investments of time and money which is why catching invasive species during the early stages of their establishment is very important.

Early Detection Rapid Response Species Protocol (EDRR)

***Park Biologists to the Rescue!*** The Early Detection Rapid Response Species Protocol, or EDRR for short, is a strategy for identifying and responding to new or emerging invasive species (plant, animal, or other organisms) before they become widespread and cause significant harm to ecosystems or human interests.

• Detection: This involves actively monitoring habitats, reporting sightings of potentially invasive species, and potentially using tools like eDNA sampling to detect their presence.
• Rapid Response: Once an invasive species is detected, the protocol outlines swift actions to prevent its establishment and spread, potentially including eradication efforts, containment measures, or other management strategies.
• GETT biologists, in cooperation with other National Park Service and Pennsylvania State biologists continually monitor park lands for EDRR species and develop an appropriate response to any new invader.

The Top 10 Least Wanted Invasive Plant List

***The list below describes our Top 10 Least Wanted List*** Among the many invasive species that our staff have documented at Gettysburg National Military Park (NMP) and Eisenhower National Historic Site (NHS), we’ve identified ten species that have some of the largest, and most negative effects, on the parks and surrounding area. These invasive plant species are categorized as both well-established and those recently discovered. Regardless of their time on and around the parks, their impacts are significant.

Each entry includes the species description, a photo, and its impact on the ecosystem. Additionally, we describe the efforts we use to combat the spread of these invasive species. Finally, we’ll go over how our visitors can help identify, report, and aid in our efforts to contest the spread of these harmful plants.

What Can You Do

As a devoted visitor to Gettysburg NMP and Eisenhower NHS, you can see the direct impact invasive species has on your parks. During the warm weather months, we host a series of Volunteer Work Days. Sign up for one or all of these to lend a hand! You can aid our staff to combat these invading species and perhaps slow or halt their march across our fields, our hills, our stone walls, our fences, or even around our monuments.

 

The Top 10 Least Wanted List: Shrubs

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  Japanese Barberry

  The dense Barberry growth creates a microclimate that is ideal for black-legged ticks (deer ticks), which are a source of Lyme disease.

• 

  Multiflora Rose

  The Multiflora Rose is commonly found throughout woodlands and fields and can cause severe skin and eye irritation in cattle.

• 

  Wineberry buds

  Vigorous growth prevents native saplings from initial development as well as regeneration after a disturbance such as a severe storm.

 

The Top 10 Least Wanted List: Herbs

• 

  Invasive Garlic Mustard

  Garlic Mustard is a toxic decoy plant that misleads some butterfly species into laying their eggs on it when no food source exists.

• 

  Japanese Stiltgrass

  Japanese Stiltgrass alters soil chemistry creating an inhospitable environment for native plant species.

• 

  Wavyleaf Basketgrass

  Wavyleaf Basketgrass is an aggressive invasive plant which grows in semi-shaded areas. It severely diminishes native plant and tree growth.

 

The Top 10 Least Wanted List: Trees

• 

  Callery Pear

  The Callery Pear blossom has an offensive smell. Its dense root growth prevents native species from growing.

• 

  Tree of Heaven

  An aggressively invasive plan which sprouts new sapling when cut and is the favorite host plant for the Spotted Lantern Fly.

 

The Top 10 Least Wanted List: Vines

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  Chinese Yam

  Chinese Yam vines can damage to trees by blocking nutrients and weighing them down, breaking off branches.

• 

  Japanese Honeysuckle

  The dense mats of Japanese Honeysuckle destroy native ground species and prevent new growth.

 

Learn How You Can Volunteer! Help Us Control Invasive Plants!

 

Volunteer Contributions

Shrubs

• Japanese Barberry: Visitors can assist park staff by cutting the stems of the Japanese Barberry while participating on Volunteer Work Days.

  • Park biologists may follow up with an application of an appropriate herbicide.

• Multiflora Rose: Visitors can assist park staff by cutting the stems of the Japanese Barberry while participating on Volunteer Work Days.

  • Park biologists may follow up with an application of an appropriate herbicide.

• Wineberry: Visitors can assist park staff by cutting the stems of the Japanese Barberry while participating on Volunteer Work Days.

  • Park biologists may follow up with an application of an appropriate herbicide.

Herbs

• Garlic Mustard: Visitors can assist park staff by cutting the stems of the Japanese Barberry while participating on Volunteer Work Days.

  • Park biologists monitor known sights throughout the growing season.

• Japanese Stiltgrass: Visitors can assist park staff by cutting the stems of the Japanese Barberry while participating on Volunteer Work Days.

  • Park biologists are studying pre-emergent herbicides to manage the plant before it starts to grow.

• Wavyleaf Basketgrass: Volunteers assist park staff by reporting sightings of the species and pulling the shallow-rooted plants by hand while participating on Volunteer Work Days.

  • Park biologists apply herbicides to the more established, larger infestations.

Trees

• Callery Pear: The most effective help is to report sightings of the trees, as pulling or cutting of the plant causes more aggressive growth.

  • Herbicides are applied to the trunks of the Callery Pear by park biologists.

• Tree of Heaven: The most effective help is to report sightings of the trees, as pulling or cutting of the plant causes more aggressive growth.

  • Herbicides are applied to the trunks of the Tree of Heaven by park biologists.

Vines

• Chinese Yam: Volunteers assist park staff by reporting sightings of the species and pulling out the plants by hand while participating on Volunteer Work Days.

  • Park biologists follow up with cutting vines and spraying herbicides.

• Japanese Honeysuckle: Volunteers assist park staff by reporting sightings of the species and cutting the vines by hand while participating on Volunteer Work Days.

  • Park biologists follow up with cutting vines rom trees, mowing affected fields and spraying herbicides.

 

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Reporting with iNaturalist