In 2009, Great Lakes IPMT helped restore 1 invaded panne at Indiana Dunes. 17 years later, native flowers now bloom in the wetland where invasive plants once formed a dense monoculture

In 2009, the Great Lakes Invasive Plant Management Team partnered with Indiana Dunes National Park to control invasive plants that had overwhelmed one of the park's panne ecosystems.

Pannes are wetlands found between sand dunes and are classified as globally vulnerable. Monitoring and inventory work at the site had begun in 2005 before the partnership with the Great Lakes IPMT.

An invaded wetland between the dunes

Wetlands support many species of plants and animals and provide ecosystem services including improved water quality, flood control and erosion control.


Pannes contain many endangered and at-risk species and are considered a priority natural resource at Indiana Dunes National Park.

One of the pannes at West Beach had become overwhelmed by invasive plants. If left untreated, the site could have threatened healthy pannes by serving as a seed source for invasive species.

Small pockets of native plants remained, providing hope that the site could be restored if the invasive plants were removed.

Invasive plants had taken over the site

The Great Lakes IPMT targeted common reed, hybrid cattails, purple loosestrife and non-native thistles.

Common reed can grow between 1 and 6 metres tall and had created a dense monoculture that choked out native plants. It spreads through clonal rhizomes, specialised stems from which new plants can grow.

The rhizomes can dominate the soil and make nonchemical management difficult within established infestations. Dead reeds also had to be knocked down to facilitate treatment the following year.

Hybrid cattail and purple loosestrife also spread through rhizomes, forming dense stands that outcompete native vegetation. Both species produce seeds that can remain in the soil for decades.

Repeated treatment supported restoration

Biologists developed the management strategy after considering the characteristics of the invasive species, the presence of remaining native plants and the remoteness of the site.

The team decided to apply herbicide for multiple consecutive years to remove invasive species and facilitate restoration.

Annual treatment was important because invasive plants continued to grow from rhizomes and the seed bank. Each year, the Great Lakes IPMT returned to the intradunal wetland to manage invasive plants through heat, humidity and difficult terrain.

After nearly two decades of consistent effort, Indiana Dunes National Park natural resource staff were able to begin restoration and revegetation.

Native flowers now bloom in the wetland

The site that had once been degraded is now a healthy panne.

The invasive monoculture has been replaced by a variety of native species, and wildflowers now bloom in the intradunal wetland where invasive grass once dominated.

Indiana Dunes National Park staff continue to monitor the panne annually to ensure the site is maintained as a healthy, high-quality and biodiverse panne ecosystem.