Sielbeck Forest Natural Area is a 385-acre Illinois state park in Johnson County that preserves forested land in southern Illinois under the management of the Illinois Department of Natural Resources. The property had belonged to Ruth and Louie Sielbeck until after Louie Sielbeck’s death, when it was offered for sale. The Nature Conservancy purchased the land in 1997 and sold it to the state the next year. The area supports outdoor recreation including fishing, hiking, and daytime hunting, with species such as largemouth bass, bluegill, deer, and wild turkey, and it is governed by statewide regulations.