What is the Oak Savanna and why is it so important?
Submitted by: Cathy Martin, Save the Dunes
An oak savanna is a mixture between the tallgrass prairies of the west and forests of the east. The low tree density and large spaces between trees create a mixture of sun and shade, allowing for the growth of native grasses and wildflowers. The convergence of prairie and forest habitats supports a diverse range of plant and animal species, which is why Miller Woods- an oak savanna site in the Indiana Dunes National Lakeshore- is the second most biodiverse area in the entire Indiana dunes region.
Once among the most common natural communities of the Midwest, oak savannas are rare and increasingly threatened habitats. In fact, less than .02% of oak savanna habitats remain in the Midwest. We are fortunate to have some of the largest protected and high-quality remnants of oak savanna here in the Indiana dunes. However, due to management limitations, reduced fire regime, invasive species, and climate change impacts, our local populations of oak savanna habitat are in decline.
Fire is a critical process for maintaining a healthy oak savanna. Scattered oaks develop into large fire-resistant trees. The movement of fire through an oak savanna ensures that the understory does not become overgrown with shrubs and small trees that absorb sunlight, water, and other resources and out-compete wildflowers and grasses. Historically, wildfires that started naturally or as a result of human disturbance maintained the savanna structure; Miller Woods is home to such high quality oak savanna habitat because it received frequent fires resulting from sparks flying off of the adjacent railroads. As population growth expanded in Northwest Indiana, wildfires were suppressed, and maintaining habitat structured required use of prescribed burns. However, due to the proximity of residential areas, policies that limit burn windows, unfavorable weather conditions, and limited staff and funding resources to implement prescribed burns, the use of fire in managing natural areas is inconsistent and, in some years, barely existent. Due to the lack of fire in oak savanna habitats over the years, many of our local populations became overgrown with aggressive and nonnative species and began to lose the very structure that defines this unique habitat.
In 2013 project funding for restoration became available due to a settlement between the Environmental Protection Agency and Dominion Energy, Inc., who owned and operated the State Line Power Plant in Hammond. An advisory committee was formed between Save the Dunes, the National Park Service, the Department of Natural Resources, The Nature Conservancy, and Shirley Heinze Land Trust to identify projects that would enhance the Indiana Dunes National Lakeshore and surrounding areas. The Oak Savanna Restoration Project was identified as a priority project for the region and received one million dollars for implementation. Work on the project began in summer 2014.
Through this project, the National Park Service has restored 1,045 acres of rare black oak savanna habitat in Miller Woods and Tolleston Dunes, and the Indiana Department of Natural Resources has restored 32 acres of black oak savanna in the Indiana Dunes State Park along trails 9 and 10. This project has helped reset the oak savanna structure by removing overgrown brush and small trees and supporting the growth of native wildflowers and grasses. This is good news for plants such as lupine, which depend on adequate amounts of sunlight to flourish. And what’s good for lupine is good for the federally endangered Karner blue butterfly, which depends on lupine for survival. Due to a range of realities including the degradation of oak savanna habitat and unfavorable conditions created by climate-related events, the Karner blue butterfly’s population has plummeted in the Indiana dunes region in recent years. Land managers and scientists fear that the butterfly may be locally extinct. This large-scale restoration project will help prevent other species from meeting a similar fate and could possibly allow for the Karner blue butterfly’s return to the dunes.
Would you like to help with the restoration of the Oak Savanna? Save the Dunes and the Indiana Dunes National Lakeshore will continue to host volunteer stewardship events to increase the number of helping hands in the field. These events are fun and educational and allow communities to be stewards of the national park in their backyard. While the Indiana Dunes National Lakeshore is small, it is a biological gem; in fact, ours ranks as the seventh most biodiverse national park in the National Park System. We want the public to play a role in maintaining the biodiversity that makes this such a unique place.
Be sure to visit Miller Woods, Tolleston Dunes, and the Indiana Dunes State Park in 2016 to see the results of the Oak Savanna Restoration Project. And mark your calendars for a hike in Miller Woods with Save the Dunes on Saturday, May 21st at 10:00am. Contact Cathy Martin for information on the hike or anything else regarding the Oak Savanna Restoration Project at Cathy@Savedunes.org .