Nonnative Species

Invasive Species

Defined by Executive Order 13112, "an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health."

 

The Canada thistle is an invasive of very high concern at Wind Cave National Park. This plant can produce up to 28,000 seeds per square foot.

NPS photo

Prairie Impacts

The prairie is a landscape which has greatly changed in the last few hundred years. Human migrations have introduced many new plants to the ecosystem, which impacts its diversity, productivity and overall health. In order to ensure the health of the prairie ecosystem, Wind Cave National Park staff work hard to control invasive weeds.

Many nonnative plant species are not edible, and can even be toxic to grazing animals. If nonnative species compete with native species for resources such as moisture and soil nutrients, the health of the prairie and available food declines.

 

High Priority Invasive Plants in Wind Cave

Click to View Common Names (Scientific Names)

Absinth wormwood (Artemisia absinthium)
Bouncing bet (Saponaria officinalis)
Bull thistle (Cirsium vulgare)
Canada thistle (Cirsium arvense)
Common burdock (Arctium minus)
Common buckthorn (Rhamnus cathartica)
Crown vetch (Coronilla [Segurigera] varia)
Dalmation toadflax (Linaria dalmatica)
Dame’s rocket (Hesperis matrionalis)
Houndstongue (Cynoglossum officinale)
Leafy spurge (Euphorbia esula)
Motherwort (Leonurus cardiaca)
Musk thistle (Carduus nutans)
Poison hemlock (Conium maculatum)
Puncture vine (Tribulus terrestris)
Russian olive (Elaeagnus angustifolia)
Scotch thistle (Onopordum acanthium)
Siberian elm (Ulmus pumila)
Smooth brome (Bromus inermis)
Spotted knapweed (Centaurea maculosa)
St. Johnswort (Hypericum perforatum)
White horehound (Marrubium vulgare)
White poplar (Populus alba)
Yellow toadflax (Linaria vulgaris)

 

Control Methods

At Wind Cave National Park, several methods for controlling invasive plants are considered:

Monitoring and inspection
This is the first step in understanding conditions in the park. By taking an inventory of invasive plants in the park, we can better understand which areas need to be focused on, and if our previous control methods for invasive plants are effective.

Mechanical
Mechanical methods of invasive weed removal include weed whacking, cutting of the plants, and mowing. This method usually proves to be ineffective because many invasive weeds spread via rhizome and root, underground parts of the plant that store nutrients. This method is therefore not used at Wind Cave.

Manual
This method involves pulling the plants by the root, and using a shovel to dig up the entire plant. Because this method is very labor intensive and doesn't always work, it is used in a limited capacity in the park.

Prescribed burn
For large, dense stands of invasives, this method may be effective. However, it is non-selective, meaning that native plants may be burned as well. It is more expensive, requiring large fire crews on site. It is not an effective control method at Wind Cave National Park.

Mulching
Mulch can be an effective strategy against invasives on a limited, selective basis. It is most useful at visitor-use sites like campgrounds and visitor centers and at archeological sites.

Chemical
Various methods of chemical spraying have proven to be a viable and safe way to control invasive plants. Great caution is used with regards to the type of herbicide used and location of spraying. Potential impacts to cave and water resources are considered before spraying.