Problematic Plant Monitoring at Lincoln Boyhood National Memorial

Japanese stiltgrass is a problematic plant at Lincoln Boyhood National Memorial. It produces up to 1,000 seeds per plant each year, which makes it challenging to control.

NPS

What Are Problematic Plants?

Sometimes plants grow in places where they don't naturally occur and some plants can cause damage to ecosystems and even harm people. Exotic plants are nonnative species that are typically introduced into an ecosystem by human actions, whether intentional or not. Invasive plants are exotic species that cause ecological or economic harm. Pest plants, which can be native species, interfere with specific management objectives and are sometimes called weeds. We refer to the collection of exotic, invasive, and pest plants as problematic plants.

Problematic Plant Management

National parks spend a lot of time trying to remove or control problematic plants to protect native plant and animal communities and visitors at parks. When a plant species is impairing park resources, managers are required to control the plant. They use five criteria to decide what other problematic plants they will control: the origin of the species, prudence of the action, feasibility of controlling the plant, the harm or impact that the plant causes, and the harm that removal of the plant could cause. Managers use environmental assessments, the professional judgment of experts, and scientific research to make these decisions. They also consult with regulating agencies and the public.

We searched for problematic plants on 77 search units in Lincoln Boyhood National Memorial. The average size of these individual, numbered search units is 2.0 acres.

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Plant Surveys

Park managers have to know where problematic plants are to control them. The Heartland Inventory and Monitoring Network collects information on the cover (a measure of how much ground is covered by the plant), distribution, and location of problematic plants at Lincoln Boyhood National Memorial. We surveyed the park in 2006, 2011, 2015, and 2019. Managers can develop management actions and track the success of their control efforts using the information from our surveys. We use an early detection watch list and a park-established watch list to search for problematic plants. Early detection species are plants that have not been detected on the park before but have the potential to grow there. Plants on the park-established watch list have been found in the park during previous surveys.

Problematic Plants on the Park

Since 2006, we have identified 45 problematic plant species at Lincoln Boyhood National Memorial; 34 of these were found in 2019. Only one plant species (common periwinkle) occupied more than 10 acres. We use ten acres as a guideline for identifying our chances of successfully controlling a plant. Crown-vetch and garlic mustard are potential candidates for eradication because there are few of them growing on the park. Other species like European privet and Japanese stiltgrass will be more challenging to control because they are growing all over the park. Japanese stiltgrass was found in 26% of the areas searched in 2006 and in 88% of the areas searched in 2019 despite recent control efforts. Park managers have to prioritize control and removal projects when there are many problematic plants. Species targeted for control should include plants that are capable of rapid spread, plants that are present in low numbers, and plants that can effectively be controlled.

Problematic Plant Species at Lincoln Boyhood National Memorial (2006–2019)

Problematic plants found at Lincoln Boyhood National Memorial (2006–2019). An asterisk (*) indicates that the species was not found in 2019 surveys.

Common Name	Scientific Name
tree of heaven	Ailanthus altissima
silktree	Albizia julibrissin
garlic mustard	Alliaria petiolata
lesser burdock	Arctium minus
Japanese barberry	Berberis thunbergii
bald brome, spiked brome	Bromus racemosus
Oriental bittersweet	Celastrus orbiculatus
bull thistle	Cirsium vulgare
sweet autumn virginsbower*	Clematis terniflora
Queen Anne's lace	Daucus carota
Chinese yam	Dioscorea oppositifolia
autumn olive	Elaeagnus umbellata
burningbush, winged euonymus	Euonymus alatus
winter creeper	Euonymus fortunei
English ivy	Hedera helix
orange daylily*	Hemerocallis fulva
common St. Johnswort	Hypericum perforatum
sericea lespedeza	Lespedeza cuneata
border privet*	Ligustrum obtusifolium
Chinese privet*	Ligustrum sinense
European privet	Ligustrum vulgare
Japanese honeysuckle	Lonicera japonica
Amur honeysuckle	Lonicera maackii
Morrow's honeysuckle*	Lonicera morrowii
bird's-foot trefoil*	Lotus corniculatus
creeping jenny	Lysimachia nummularia
yellow sweetclover	Melilotus officinalis
Japanese stiltgrass/Nepalese browntop	Microstegium vimineum
white mulberry	Morus alba
reed canarygrass*	Phalaris arundinacea
Canada bluegrass *	Poa compressa
Canada/Kentucky bluegrass complex*	Poa compressa/pratensis
Kentucky bluegrass	Poa pratensis
Japanese knotweed	Polygonum cuspidatum
sulphur cinquefoil*	Potentilla recta
Callery pear	Pyrus calleryana
black locust	Robinia pseudoacacia
multiflora rose	Rosa multiflora
tall fescue	Schedonorus arundinaceus
crownvetch	Securigera varia
Johnsongrass	Sorghum halepense
spirea sp.	Spiraea sp.
common mullein*	Verbascum thapsus
common periwinkle	Vinca minor
Chinese wisteria	Wisteria sinensis

European privet seedlings like the one in this photograph grow when seeds are deposited by birds and other wildlife. They eat the fruits and excrete the seeds, dispersing them widely.

NPS/Sam Sheline

Species Spotlight: European Privet

European privet (Ligustrum vulgare) is a perennial shrub in the olive family (Oleaceae). Native to Europe and North Africa, it was brought to North America in the 1700s and 1800s as an ornamental plant and has been widely used for hedges. It grows aggressively, forming dense thickets that outcompete native plants. This shrub's small white flowers bloom in June and July, and the small, shiny bluish-black berries mature in September and October. European privet can establish in forests, grasslands, old fields and other disturbed areas. At Lincoln Boyhood National Memorial, this plant occupied less than 2 acres in 2019, but was found in 82% of the areas searched.

For More Information

Read the Full Report.

Check back later for updates. We will update this page each year as we gather information.

Visit the Heartland Inventory & Monitoring Network website.