Local students control invasive plants at Indian Dunes National Lakeshore. Porter County Indiana. (Natioanl Park Service Photo) - Photo Credit: n/a

Indiana’s Lake Michigan coastal ecosystems support exceptional plant and animal diversity, including dunes and adjacent oak savannas that are home to the threatened Pitcher’s thistle and endangered Karner blue butterfly.  Approximately 30 other State-listed species also occur in these important coastal habitats within Indiana Dunes National Lakeshore.

These rare plant and animal communities are at great risk.  Invasive plants have become well established throughout much of Indiana Dunes and recent surveys confirm invasive species are quickly overtaking the rare plant and animal habitats.  Invasive plants such as black locust, Oriental bittersweet, Canada thistle and non-native honeysuckles effectively force out native flora and fauna through competition, resulting in degradation and eventual loss of rare communities such as oak savanna, wetland, prairie, and foredune. 

Coastal Program funding was used for on-the-ground habitat restoration by treating the highly invasive plants that threaten habitat occupied by Karner blue butterflies and Pitcher’s thistles and improving habitat for Karner blue butterflies through selective canopy thinning.  Field staff searched identified Pitcher’s thistle and Karner blue butterfly habitats for invasive plant species.  When found, plants were treated using a variety of methods including hand pulling, cutting, and herbicide application. 

All treatments were mapped and recorded using GPS units.  Canopy thinning was conducted in select oak savanna communities to improve conditions for the Karner blue butterfly and wild lupine, its sole larval food source.  Habitat was improved by cutting trees and shrubs and applying herbicide to cut stumps to prevent resprouting in order to create canopy gaps and increase light levels necessary for wild lupine. 

Approximately 68 acres of land were searched and treated for non-native plants during the course of this project.  Areas treated were selected to provide the maximum benefit to the federally endangered Karner blue butterfly or federally threatened Pitcher’s thistle habitats. 

Invasive plant species treated included black locust, buckthorn, honeysuckle, jimsonweed, Lombardy poplar, multiflora rose, non-native thistle, autumn olive, Oriental bittersweet, petioled sunflower, privet, spotted knapweed, sweet clover, and tree of heaven.  In addition, approximately four acres of Karner blue butterfly habitat were improved through selective thinning of trees and shrubs.