NPS Photo by Mike Laycock
Countering the Alien Invasion
Wind Cave National Park is located at a crossroads - a place where the prairie meets forest, and eastern and western grasslands merge. This convergence allows for a greater diversity of native plant species and a larger variety of wildlife. However, lurking amongst these native plants are aliens who do not belong. These are not invaders from a far away planet but plant species from other parts of our very own earth.
Research conducted by Cornell University estimated that in dollars alone, the European purple loosestrife costs the U.S. economy $45 million dollars in loss of food for grazing animals and in attempts to control its spread. Alien plants spread rapidly because the animals, diseases, and competing plants that kept them in check in their native lands are missing.
At Wind Cave National Park, the costs are more than economic. Invasive species such as Canada thistle, leafy spurge, and horehound can out-compete native plants for water, sunlight, and nutrients. When this happens the populations of native plants are reduced and the animals that depend on those plants struggle for survival. This invasion of alien species reduces the diversity of the prairie; the aliens take over parts of the prairie creating monocultures where once dozens of native plants thrived.
Park biologists are constantly waging battle against these alien species. Some methods used to control them include manual control such as hand pulling or mowing, biological controls (using natural enemies of non-native plants such as insects), prescribed fire, and, in a few cases, herbicides.
If you see staff from the resource management team mowing the prairie or working on a prescribed fire, you are witnessing how we are working to accomplish the National Park Service's mission of preserving the natural plant and animal communities. Keeping invasive plant populations in check is vital to that mission.