These landscape types were not recognized and described by landscape ecologists until about the early 1980’s. Black and white oak species are adapted to growing on dry, sandy sites. At maturity they exhibit an open park-like condition with broad canopies and twisted, knotty trunks.
This habitat structure is particularly attractive to red-headed woodpeckers. Unlike closed-canopied forests that are typically described as having multiple layers—ground cover, shrub layer and under story trees—the oak woodland only has a herbaceous ground cover layer.
Bottlebrush grass, two-flowered Cynthia and starry campion are typically found in this semi-shaded environment. The occurrence of periodic ground fires before European settlement and fire suppression originally kept the understory tree layer absent. The widely-spaced canopy trees allow increased light to penetrate to the ground, thus encouraging a diversity of herbaceous plants—many found in more open prairie sites.
Unlike other tree and shrubs species, seedlings and saplings of black and white oak rapidly re-sprout after a fire, and the bark of the larger specimens is resistant to fire damage. Merry Lea is completing restoration of the Luckey Oak Woodland which originated on an ancient sand dune system off the NE corner of High Lake. It has also begun restoration of an oak woodland on an small glacial kame on the south edge of Edwards Wetland and of a white oak woodland on the west slope of a glacial esker in the Merry Lea State Nature Preserve.
This landscape type is represented by widely-spaced oak trees with broad crowns growing amidst a herbaceous ground cover of plants representative of the prairie—but which can tolerate some shade.
While burr oak and white oak are the dominate trees in some moister savannas, Merry Lea has two sites representative of black oak savannas established on sandy soils. Little bluestem, butterflyweed and tall anemone are plants typical of these sites. In 1995 wild lupine, the only food source of the endangered Karner blue butterfly, was introduced.