Tallgrass prairies and oak savanna are among the most decimated and threatened landscapes in the Midwest and the world. The original grasslands in Wisconsin included the tallgrass prairie, which was intermixed with oak savanna. The Illinois portion of Hackmatack National Wildlife Refuge historically consisted of wetlands, oak savanna, woodlands, and prairie. Today, with the exception of existing conservation estate land, only small, often isolated pockets of these habitats exist on the refuge. The landscape also includes the sculpted remnants of moraines, kames, kettle marshes, and bogs from its glacial past.